Grade Nine Science

Space Unit

• http://www.youtube.com/watch?v=SWOoV4b49SI

What can we see in the sky?

• What are some things that we can see in the sky?

• Something that people have noticed and documented throughout time is that there are patterns in what we see in the sky.

• Constellations

• North Star

• Moons

• Planets

• The study of what is beyond Earth is called Astronomy.

Star Constellations

• Groups of stars that seem to form shapes and patterns are called constellations.

• Some stars look as though they are close together when some are really much farther from Earth than others.

• Constellations have been used for thousands of years as calendars, timekeepers and direction finders for travellers.

• http://science.nationalgeographic.com/science/photos/stars-gallery/light-echo.html

• The solar system consists of our sun and all the objects that travel around it.

• Planets and moons are nonluminous. They do not emit their own light. We can see them in the sky only when the light from the Sun reflects off them towards Earth.

• Only 5 of the planets in our solar system can actually be seen with an unaided eye: Venus, Mars, Jupiter, Saturn and Mercury.

How big is the universe

• http://www.youtube.com/watch?v=Zr7wNQw12l8

What is the difference between Stars and Planets?

Feature Planet StarLocation : In the solar system Far beyond the solar

system.

Distance from Earth: Fairly near Very far

Real Size: Smaller than most stars Usually larger than planets

Reason why we see object:

Reflects light from the sun

Emits its own lights.

Surface Temperature: Usually cool or very cold

Very hot

What is the object made of:

Usually rocks or gases. Gases under high pressure and temperature.

Long-term observable feature

Very slowly wanders through constellations

Appears to move through sky as part of a constellation.

Earth’s Rotation

• The Earth rotates (spins) on an axis.

• It takes 24 hours to do one rotation around its axis.

• This motion causes most stars, sun and moon to appear to rise in the east and set in the west.

• The Earth’s axis is an imaginary line that connects the North Pole to the South Pole.

• http://axiomsun.com/home/video/time_lapse_showing_earths_rotation.html

• http://videos.howstuffworks.com/hsw/10000-the-moon-tides-video.htm

Earth’s Revolution

• The Earth’s Revolution is the motion of one object travelling around another.

• It takes Earth one year to travel and revolve in a circle around the sun.

• This allows us to see different stars and constellations during different seasons.

• The angle of the Earth’s axis and the Earth’s Revolution causes the different seasons.

What sound does the Earth make

• http://www.youtube.com/watch?v=5AVHXMLDvWA&feature=related

Sound of the Sun

• http://www.youtube.com/watch?v=pGwDdTZBAEY&feature=related

Hubble Telescope

• Part 1

http://www.youtube.com/watch?v=SpkrVw_E6Nw&feature=related

Part 2

http://www.youtube.com/watch?v=upXTZE57Z5U&feature=related

• Part 3

• http://www.youtube.com/watch?v=xt9Bvc8s_d0&feature=related

• Part 4

• http://www.youtube.com/watch?v=1_9gsFcKh9I&feature=related

• Part 5

http://www.youtube.com/watch?v=gnCvHnlNT7c&feature=related

Part 6

http://www.youtube.com/watch?v=-PwkW76jR1w&feature=related

• Part 7

http://www.youtube.com/watch?v=fqYshf-jc7U&feature=related

Part 8

http://www.youtube.com/watch?v=23MXsnpC-5Y&feature=related

Pictures from the Hubble

• http://www.youtube.com/watch?v=-_Fs8oIdD7o&feature=fvw

Hubble Deep Field

• http://www.youtube.com/watch?v=mcBV-cXVWFw

Parallel Universe

• http://www.youtube.com/watch?v=XmyrE9I8HNg

• http://www.youtube.com/watch?v=42-BpCivYJU&feature=related

• http://www.youtube.com/watch?v=no_fOg9KNP4&feature=related

• http://www.youtube.com/watch?v=BhB8EQPjC8c&feature=related

Universe Mysteries

• http://www.youtube.com/watch?v=U3skOSgFS6A&feature=related

• http://www.youtube.com/watch?v=06aw81kS53I&feature=related

• http://www.youtube.com/watch?v=p_DPbkegBGo&feature=related

• http://www.youtube.com/watch?v=9VoxMwYC_U4&feature=related

• http://www.youtube.com/watch?v=DfgKJFSWR14&feature=related

How Big is the Sun?

How big is the sun

• http://www.youtube.com/watch?v=I34FNr_peUk&feature=related

What is the Universe?

• What things do we consider to be in the Universe?

The universe is everything that exists, including all matter and energy everywhere.

The Solar System

• What planets make up our solar system?

• (In order from the sun) , Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto (dwarf planet).

• The planets revolve around the Sun in paths called orbits.

• The orbits of most planets are nearly circular, with the Sun at the center of each orbit.

• The period of time for one revolution around the sun is called one orbital period.

• The earth’s orbital period is about 365 days.

• The earth’s rotation around its axis once every 24h causes our day and night cycle.

• The order from biggest planet to smallest is as follows.

• The largest planet is Jupiter. It is followed by Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and finally, tiny Pluto (a dwarf planet). Jupiter is so big that all the other planets could fit inside it.

The Inner vs. Outer Planets

• The inner planets (those planets that orbit close to the sun) are different from the Outer planets (those planets that orbit farther from the sun).

• The inner planets are: Mercury, Venus, Earth, and Mars. They are relatively small, composed mostly of rock, and have few or no moons.

• The outer planets include: Jupiter, Saturn, Uranus, Neptune, and Pluto (a dwarf planet). They are mostly huge, mostly gaseous, ringed, and have many moons (again, the exception is Pluto, the dwarf planet, which is small, rocky, and has one large moon plus two tiny ones).

A closer look at the Sun

The Sun Compared to Other Stars

Exploring the Solar System: Where Exactly Are We?

• http://personal.nbnet.nb.ca/hartt/Solar%20system/sun.htm

• http://personal.nbnet.nb.ca/hartt/Solar%20system/doomsday.htm

• The planets of the solar system are made up of different combinations of chemical elements which is why no two planets are the same.

• Scientists have determined that throughout the solar system there are four common elements: hydrogen, helium, oxygen and carbon.

• These common elements are found under high pressure on the Sun and on the four largest planets.

Probes to the Planets

• A space probe is an unpiloted spacecraft sent to explore parts of the solar system beyond Earth.

• The probe collects information and transmits it back to Earth.

Mercury

• Closest planet to the Sun.

• Recieves 10 times the amount of sunlight than Earth giving it 400 degrees celsius daytime temperatures.

• It has no atmosphere to trap heat so nighttime temperatures fall to –180 degrees celsius.

• Has craters all over planet.

Venus • Has a thick atmosphere that can reflect sunlight. • Brightest planet in the sky.• Second planet from the Sun.• Atmosphere is mainly made of carbon dioxide.

This gas acts like the glass of a greenhouse, keeping the surface temperatures high enough to melt lead.

• Venus is hard to explore because of its thick atmosphere.

Earth

• Third planet from the Sun.

• Atmosphere mainly contains nitrogen, oxygen, and water vapour.

• There is also a small amount of ozone that filters out some of the Sun’s radiation but lets enough through for life on Earth.

• Water covers 70% of Earth.

Mars

• Fourth planet from the Sun.

• Called the Red Planet because of the reddish color of its soil.

• Space Probe, Pathfinder, landed on Mars in 1997 and provided us with first hand photos of the planet.

• Evidence that Mars once had volcanoes, glaciers, and floods of water.

Jupiter

• Fifth planet from the sun.

• Largest of all planets.

• 11 times the diameter of Earth.

• Has a giant red spot where huge hurricanes form fed by constant high winds.

• Has 16 moons.

• Has orbiting rings of rock.

Saturn

• 6th planet from the sun

• Second largest planet.

• Atmosphere is cloudy because of its quick rotation.

• Has over 1000 separate rings.

• Average temperature is – 180 degrees Celsius.

Uranus

• 7th planet from the Sun.

• 4 times the size of Earth.

• Rotates on its side.

• Atmosphere is mainly made up of hydrogen with some helium and methane.

• Has winds that blow up to 500 km/ h.

• Takes 84 years to complete one orbit.

Neptune

• 8th planet from the Sun.

• First planet to be located by mathematical predictions.

• Orbits the Sun every 165 years.

• 4.5 billions km away from the Sun.

• Windiest planet 1000+ km/h

• Made mainly of ice

• http://www.youtube.com/watch?v=29wfzotaBIg

Pluto

• The International Astronomical Union (IAU) formally downgraded Pluto from an official planet to a dwarf planet.

• According to the new rules a planet meets three criteria: it must orbit the Sun, it must be big enough for gravity to squash it into a round ball, and it must have cleared other things out of the way in its orbital neighborhood.

• Pluto takes 248 years to orbit the Sun.

Planetary Moons

• Large natural objects that revolve around planets are called satellites or moons.

• The moon we have orbiting Earth has no atmosphere.

• 1610 Galileo was the first person to see four of Jupiter’s moons.

Planetary Moon count in 1998

Planet Number of known moons

Mercury 0

Venus 0

Earth 1

Mars 2

Jupiter 16

Saturn 18

Uranus 17

Neptune 8

Pluto 1

Planetary Moon Count in 2008Planet Number of known

moons

Mercury 0

Venus 0

Earth 1

Mars 2

Jupiter 63

Saturn 60

Uranus 27

Neptune 13

Pluto 3

• http://www.windows.ucar.edu/tour/link=/our_solar_system/moons_table.html

Asteroids

• rocky objects that travel throughout space.

• They are usually smaller than planets but larger than meteorites.

• Between Mars and Jupiter there is ring of asteroids called an asteroid belt.

• 1937 an asteroid named Hermes came within 800,000 km of Earth.

• Asteroids are rich in minerals which humans may have to mine someday.

Meteoroid • A lump of rock or metal that is trapped by the

Earth’s gravity and pulled down through the Earth’s atmosphere.

• As it falls it rubs against the molecules of the air causing friction. This friction causes the meteoroid to become hot and vaporize.

• This produces a bright streak across the sky.

• If the object is large enough to hit the ground before totally vaporizing, it is called a Meteorite.

Comets

• A comet is a chunk of frozen matter that travels in a very long orbit around the Sun.

Distances in Space

• Distances in space are very large, so scientific notation is used to abbreviate these large measurements.

• Using this notation, a number is written with a digit between 1 and 9 before the decimal, followed by a power of 10.

How are Distances Measured in Space?

• To measure long distances with as much accuracy as possible, they use the largest baselines available.

• One way that scientists measure distances in space is to use the diameter of the Earth. This method could be used to determine the distance to the moon or a nearby planet.

• The largest baseline available is the diameter of the Earth’s orbit. This is used to help scientists calculate distances to the stars nearest to our solar system.

• The distance from our Sun to the next nearest star that you can see without a telescope is about 4.1 x 1013 km. This star is called Alpha Centauri.

• The light year is another measurement of distance that scientists use.

• A light year is the distance that light travels in one year.

• Light travels at about 300, 000 km / second.

• In one year it can travel 9.46 x 1012 . So the distance to the nearest star is 4.3 light years away.

The Sun: An Important Star

• The sun provides us with the energy needed by all plants and animals on Earth

• It’s gravitational pull keeps us in our steady orbit.

• Because the Sun is the closet star to Earth, it is the brightest object in the sky. It gives off so much light energy that you cannot see the other stars until the Sun has set.

• The Sun’s energy comes from a process called Nuclear Fusion.

• Nuclear Fusion occurs because inside the Sun the temperature and pressure are so high that substances fuse (join together) to form new substances.

• In this process, large amounts of heat, light and other forms of energy that travel out from the Sun through Space.

• Every second the Sun makes more energy than humans have used throughout our entire history.

• Scientists have predicted that the Sun has been producing energy for 5 billion years and predict that the Sun will continue producing energy for about another 5 billion years.

• Solar flares emit charged particles, which travel much slower than light.

• When these particles reach Earth they are focused by the Earth’s magnetic field, at the north and south poles.

• These charged particles produce the Northern Lights and Southern Lights.

Characteristics of Stars

• The color of stars tell us something about their temperature.

• A relatively cool star glows red.

• A very hot one glows a bluish-white or even blue.

• A spectroscope is an instrument used by astronomers to look at the light given off by the Sun and other stars.

• This device splits light into a pattern of colors so we can see them as separate lines of color.

• It can also tell what chemical elements make up a star, how much of each element each star contains, the temperature of a star and the direction the star is moving.

Death of a Star

• http://www.youtube.com/watch?v=vCMXV8j2GtE

• http://www.youtube.com/watch?v=ysJ4Nj33rIo&feature=related

• Stars are also classified by their brightness.

• There are six categories, with the brightest stars called first magnitude and the faintest stars called sixth magnitude stars.

• Apparent Magnitude – how bright a star appears to you.

• Absolute Magnitude – actual amount of light given off .

The Life of a Star

• Stars follow a predictable series of stages: they are born, they develop and die.

• Gravity is the force that pulls objects towards each other. The more mass that an object has, the more gravity it exerts.

The Sun has stronger gravity than Earth.

The force gets smaller as the distance between objects increases.

How do Stars form? • All stars begin their lives in nebulas.

• Nebulas are huge clouds of dust and gases, mainly hydrogen and helium.

• Dust and gases swirl around, breaking into clumps and contracting because of gravitational forces.

• As the dust and gasses swirl around they become bigger and their gravitational force becomes stronger.

• More particles begin to pack together and eventually the clumps are dense and not enough for nuclear fission to start.

• No two stars are the same.

• Stars the size of the Sun or smaller are called Red Giants.

• Stars with masses 10 times or more larger than the Sun’s become Red Supergiants.

• A star the size of the Sun or smaller is said to have “die” when the nuclear reactions die down, the core shrinks and the outer layers of the star drift away. This becomes a dwarf star.

• Dwarf stars are stars with a higher temperature than red or yellow stars.

Supernovas

• A supernova is an enormous explosion that occurs at the end of a large star’s life.

• By this stage the star has used up the fuels needed to produce energy by the process of nuclear fission.

Neutron Stars• When a star is about 10 times the mass of

the Sun dies, the resulting core is called a neutron star. This star is composed of neutrons.

• A Pulsar is a type of a neutron star that emit pulses of very high radio waves.

• Pulsars are very small, about 20 km in diameter with very dense with the mass of a normal star.

Black Holes

• When a star about 30 times the mass of the Sun dies, the resulting core is called a black hole.

• A black hole is a small, very dense object with a force of gravity so strong that nothing can escape from it.

• Even light cannot be radiated away from its surface.

Video

• http://www.youtube.com/watch?v=mcBV-cXVWFw

Unit 1- Matter

• What is matter?– Matter is anything that has mass and takes up

space.

• Can matter change?– Provide examples. (Snow melting, water

boiling, water freezing, concrete hardens, paper yellows.)

1.2 Properties of Matter

• What do we mean by the properties of an object? – A property is simply a characteristic that we

can use to describe something.– There are physical properties and chemical

properties.

1.2 Physical Properties of Matter

• A physical property does not involve a substance becoming a new substance.

• There are many types of physical properties that you may want to describe:– Colour - red, green, blue…?– Texture - smooth, fine, coarse…?– Taste - sour, salty, sweet, …?

1.2 Other Physical Properties of Matter

• States of matter at room temperature – solid, liquid, or gas.

• Hardness is the measure of the resistance of a solid to being scratched or dented.

• Malleable is the ability of a solid to be hammered or bent into different. Aluminum foil is malleable. Gold is malleable since it can be hammered into thin sheets.

1.2 Other Physical Properties of Matter

• Copper is ductile since it can be pulled into wires.

• Ductility is the ability of a solid to be pulled into wires.

• Melting and boiling points - the temperatures at which a substance changes state from solid to liquid, and from liquid to gas.

• Crystal form. the structure (blocks, cubes, etc.) of the tiny particles of a solid that are repeated throughout a sample of that solid (i.e. salt crystals all have the same shape)

• Example, salt.• Solubility is the ability of a substance to

dissolve in a solvent such as water. Salt is soluble while pepper is not. Oil is also not soluble.

• Viscosity – is how easily a liquid flows: the thicker the liquid, the more viscous it is

• Density – the amount of matter per unit volume of that matter

1.2 Chemical Properties of Matter

• A chemical property describes the behaviour of a substance as it becomes a new substance.

• Combustibility describes the ability of a substance to react with oxygen to produce carbon dioxide, water and energy. If a substance is combustible or flammable, it will burn when exposed to a flame. A substance that will not burn is described as nonflammable.– List some materials that are combustible. – List some materials that are nonflammable.

1.2 Chemical Properties of Matter

• Reaction with acid. The ability of a substance to react with acid is a chemical property. – Name some substances that react with acids such as

vinegar.– Would you drink acid?– Look at the side of a Coke can.

1.5 Density

• Which is heavier: a 12 inch bar of gold or a pillow full of feathers?

• A 12 inch bar of gold weighs more than a pillow full of feathers even though the pillow takes up more space. Why?

• Gold is more dense. It has more matter per unit volume.

1.5 Density

• Density is the amount of matter per unit volume of that matter.

• Density(D) = Mass(m) / Volume(V)

• If you know any two of the three variables (D,m, or V), you can solve for the third.

m = D x V V = m / D

Sample density question #1

If a rock has a mass of 49 g and occupies a volume of 7 cm3, what is the density?

D = m / V

= 49 g / 7 cm3

= 7.0 g/ cm3

Solve these sample density questions

1. An object has a mass of 250 g and occupies a volume of 14.5 cm3, what is the density?

2. A piece of wood occupies a volume of 46 cm3 and it has a mass of 100 g. What is the density of the wood?

3. An unknown metal has a density of 2.6 g/cm3 and a mass of 15 g. How much volume does this piece of metal occupy?

4. A sample of a particular liquid has a density of 6.85 kg/L and it occupies a volume of 3.4 L. How much does this particular sample weigh?

Answer to question #1

D = m / V

= 250 g / 14.5 cm3

= 17.24 g/ cm3

Answer to question #2

D = m / V

= 100g / 46 cm3

= 2.17 g/ cm3

Answer to question #3

D = m / V

V = m / D

= 15 g / 2.6 g/cm3

= 5.77 cm3

Answer to question #4

D = m / V

M = D x V

= 6.85 kg/L x 3.4 L

= 23.29 kg

** Note that volume can be expressed as cm3, m3, ml or even L.

Hand out WHMIS Table

Assignment #1

Create a simple map of your home and indicate where you would have found products with some of the hazardous household product symbols that we have discussed.

Approximate Densities of Some Common Materials

Substance Den sity

kg/m3 g/cm3

Gold 19300 19.3

Silver 10500 10.5

Aluminum 2700 2.7

Ice 920 .92

Wood (birch) 660 .66

Distilled Water 1000 1.0

Water is more dense than ice!

• Why is this so important?– It means that ice floats in water instead of

sinking. Think of the poor fish if this was the not the case.

• Why is ice less dense than water?– When water freezes, it expands which means

that the same mass of water is spread over a greater volume.

Homework

• Answer questions 2,3,4 on page 25 of the text.

Physical and Chemical Changes

A burning candle – what happens?

• As the candle burns, the wax melts ( a solid becomes a liquid), and then it hardens (a liquid becomes a solid). These are physical changes.

• The wax also combusts producing heat and light. This chemical change involves the wax becoming carbon dioxide, water and energy.

What is a physical change?

• In a physical change, the substance involved remains the same substance, even though it may change state or form. When candle wax melts, it is still wax.

• Changes of state – melting, boiling, freezing, condensation, and dissolving – are physical changes .

• Most physical changes are easy to reverse.

What is a chemical change?

• In a chemical change, the original substance is changed into one or more different substances that have different properties.

• As candle wax melts, some of the wax particles combine with oxygen to produce water vapour, carbon dioxide, heat and light.it is still wax.

• Chemical changes always involves the production of new substances. Examples include burning, cooking and rusting.

• Most chemical changes are difficult to reverse.

Physical and Chemical Changes Video

• http://ca.video.search.yahoo.com/video/play?p=physical+and+chemical+properties&ei=UTF-8&fr=yfp-t-501&fr2=tab-web&tnr=21&vid=000139877548

Clues That a Chemical Change Has Happened

• A colour appears.

• Heat or light is given off.

• Bubbles of gas are formed.

• A solid material forms in a liquid.

• The change is difficult to reverse.

Models of Matter: The Particle Theory

• There are 4 principles to Particle Theory.1. All matter is made up of tiny particles.

2. All particles of one substance are the same. Different substances are made of different particles.

3. Particles are always moving. The more energy the particles have, the faster they move.

4. There are attractive forces between the particles. These forces are stronger when the particles are closer together.

2.1 Mixtures, Substances and Solutions

• Pure substances only contain one type of particle.

Ex.) Aluminum foil contains only aluminum foil particles.

Mixture

• A mixture contains at least two different pure substances.

• Heterogeneous Mixture is when particles don’t mix well with one another. Each part can be visibly seen.

Example: Pizza.

Solution

• A solution may be made up of liquids, solids, or gases. Air is a solution of gases.

Element

• Elements are pure substances that cannot be broken down into simpler substances.

Compounds

• Compounds are pure substances that contain two or more different elements in a fixed proportion.

• They are formed when elements combine together in chemical reactions.

• For example, in water there is always twice as many particles of hydrogen as particles of oxygen.

Molecules

• When two or more atoms join together, a molecule is formed.

• Molecules can contain two atoms or many thousands of atoms.

• For example, in the element of oxygen there are two oxygen atoms in each molecule.

Naming CompoundsHow Elements Combine

• Rule 1: Metals combine with nonmetals in many compounds.

• Rule 2: Write the name of the metal first and the nonmetal second.

• Rule 3: Change the ending of the non-metal to “ide.”

• Rule 4: Each atom has its own combining capacity.

• Rule 5: Atoms combine so that each can fill its combining capacity.

Ionic Compounds• Ionic Compounds are usually made of a

metallic element(s) and a non-metallic element(s).

• Ionic compounds are named using the full name of the metal followed by a shortened name of the nonmetal with an -ide ending.

• The shortened name of the nonmetal is usually the first syllable of the name of the nonmetal.

• http://www.saskschools.ca/curr_content/science10/unitb/namionic.html

Let’s Name Some Compounds

• CaO (lime) ► 1 atom chlorine, 1 atom oxygen.

combination of Calcium and Oxygen

Calcium Oxide

* CaCl2 ► 1 atom calcium, 2 atoms of chorine.

combination of Calcium and Chlorine

Calcium Chloride

Try Some on Your Own• AlCl3 =

• NaBr =

• KF =

• AgO =

• Al2O3 =

Combining Capacity

• The ability to combine with other elements.

3.2 Developing Models of Matter

• Throughout time, scientists have looked at the evidence around them, in an attempt to explain it.

• Scientists have developed many models of matter.

• These models have been modified, combined, or rejected as new evidence was discovered.

John Dalton’s Atomic Model

• In this model, an atom is a solid sphere.

• Dalton’s model states that matter must contain positive and negative charges.

• Opposite charges attract and like charges repel.

• Atoms combine to form molecules because of electrical attractions between atoms.

• Ion – an atom that has become charged by gaining or losing one or more electrons.

3.4 Inside the Atom

• Subatomic particles – “pieces” of an atom.

The particles that atoms are made of.

• Electrons and protons are subatomic particles.

Electrons and Protons

• Electrons are negatively charged particles.

• Neutrons are neutral particles

• Protons are positively charged particles.

• Protons are important because the number of protons in an atom determines what the atom is. For example, any atom with one proton is a Hydrogen atom.

• The number of protons in an atom is called an atomic number. If you know the atomic number of an atom then you know how many protons and electrons that atom contains.

• The mass number represents the sum of protons and neutrons of an atom.

• Calculating the number of neutrons an atom has:

# of neutrons = mass number – atomic number

Standard Atomic Notation

• An internationally recognized system that allows anyone to communicate information about any atom.

• Write the chemical symbol of the atom and place the atomic number to the lower left and the mass number to the upper left.

3.4 Bohr’s Planetary Model of the Atom

• Bohr suggested that: • Electrons move around the nucleus in circular

paths called orbits, like planets around the sun.• Each electron has a definite amount of energy. • The order of filling of electrons in the first three

orbits is 2, 8, 8. • Electrons are more stable when they are at the

lower energy.

Assignment

• Draw Bohr-Rutherford diagrams for the first 20 elements of the periodic table.

4.1 Organizing Elements

• One quality that could be measured for an element was its atomic mass.

• Atomic mass is the average mass of an atom of an element.

Dmitri Mendeleev

• Mendeleev was the first person to organize the first periodic table by arranging the elements in order of increasing atomic mass.

• When an element or group of elements seemed to repeat properties he had seen before, he started a new row.

• He eventually found that elements with similar properties fit into the same vertical columns.

Mendeleev’s Periodic Law

• If the elements are arranged according to their atomic mass, a pattern can be seen in which similar properties occur regularly.

• Mendeleev invented the periodic table by looking at patterns in the properties of different groups of elements.

Questions

• Do questions on page 108

# 1 - 5

Noble Gases

• Noble Gases are the elements that occupy the far right column of the periodic table.

( He, Ne, Ar, Kr, Xe, Rn )

* All gases at room temperature, the noble gases are often called inert gases because they are so unreactive, almost never forming chemical compounds.

Alkali Metals

• The elements that occupy the far left column of the periodic table are called Alkali Metals.

• These elements are extremely reactive.

Halogens

• Halogens occupy the 17th column of the periodic table. ( F, Cl, Br, I, At)

• These elements are the most reactive non-metals.

Metalloids

• Metalloids are elements that possess both metallic and nonmetallic properties.

• They are found in different groups on the far right side of the periodic table.

• Examples: Silicon, boron, germanium, arsenic, selenium, antimony, tellurium, polonium, and astatine are all metalloids.

• Do questions on page 47

• # 1 - 5

Homework

• Answer questions 2 and 3 on page 30.

Corrosion

What is corrosion?

• Corrosion is the slow chemical change that occurs when a metal reacts with oxygen from the air. This chemical reaction forms a new substance called an oxide.

• Different kinds of corrosion:– Rusting– Aluminum corrosion– Silver tarnish

Rusting

• Rusting is a chemical change that involves iron, oxygen from air and water, and salt or other minerals that may be in dissolved in the water.

• Where do we normally see rust?

• What can we do to prevent rust?

Aluminum Corrosion

• Aluminum has a chemical property similar to iron in that it reacts with oxygen to form an oxide.

• The aluminum oxide that forms is strong and it is unaffected by water.

Silver tarnish

• Unlike iron and aluminum, silver does not react with oxygen but it does react with sulphur.

• Sulphur is found in– Mustard– Eggs– Acid rain

• Silver sulphide causes silver to develop a black coating. • The black layer is annoying but it can be removed by

polishing the silver.

Preventing Corrosion

• There are many ways to prevent corrosion:– Painting metal prevents oxygen from getting at

the metal– Use plastics instead of steel– Cathodic protection – using one metal to attract

corrosion(oxygen) from another

Combustion

• In combustion, a substance reacts rapidly with oxygen and releases energy.

• The energy may be in the form of heat and light.

• Many substances can act as fuels. Eg. Wood, diesel oil, and kerosene

CombustionThe Fire Triangle

• The fire triangle is a convenient way to remember the three components of any combustion reaction.

• Removing any one of these makes the triangle incomplete and puts out the fire.

Oxygen

Heat

Fuel

CombustionFossil Fuels

• Fossil fuels were formed from plants, animals, and micro-organisms that lived millions of years ago.– Include coal, oil, natural gas and gasoline

• Fossil fuels are made up of hydrocarbons

• The main products of burning fossil fuels is carbon dioxide and water vapour

CombustionFossil Fuels

Hydrocarbon + oxygen => carbon dioxide + water reactants products

CombustionPollution

• Under ideal conditions, the combustion of hydrocarbons produces only carbon dioxide and water.

• What happens if there is not enough oxygen or if the hydrocarbons are not pure?– Carbon monoxide, sulphur dioxide, and nitrogen

oxides may be produced.– These are all pollutants.

Homework

Answer questions 1-5 on page 39