•Vocabulary• Atoms• Element• Valence electrons• Compound• Molecule• Ion

•Before You Learn About the Organic Macromolecules…• You must understand that all bigger molecules are built of smaller pieces.

• Everything of atoms…• Sometimes arranged into basic molecules.

• These smaller pieces are called…

• These will sometimes be called…

• What is a subunit?• Something that is combined with other subunits to build

something bigger.

•Atoms

• All matter is made of very small particles called atoms.

• These are the most basic subunit of everything, including life.

• An atom is the smallest unit of matter that cannot be broken down by chemical means.

• Every living and nonliving thing is made of matter. • Matter is anything that has mass and takes up space.

•Atoms• The atom is composed of three main types of smaller particles.

• Protons: positively charged particles.

• Neutrons: particles with no charge.

• Electrons: negatively charged particles.

•Atoms• The particles are in two specific areas:

• The nucleus.• The electron cloud.

• Protons and neutrons are in the nucleus.• Electrons are in various energy levels contained in the electron cloud around the nucleus.

•Atoms, continued• 99+% of the atom’s mass is made up

of the protons and neutrons found in the nucleus.

• The other <1% of the atom’s mass is found by adding up all the individual electrons.

• The nucleus takes up less than 1% of the atom’s physical space… its volume, however.

• 99+% of the atoms actual space is the electron cloud where the electrons are zooming around at nearly the speed of light.

• Technically, we are 99% empty space!

Electron Cloud

Nucleus

•Quick Facts. Put an atom into perspective.• If you used a stadium to model and atom…

• The Houston Astrodome (Home of the Houston Astros…a baseball team) seats 60,000 fans, covers 9 acres and the dome rises to a height of 200ft.

• If you could blow up an atom to the size of this stadium a basketball could represent the volume of an atom's nucleus.

• The rest of the open area is the volume of where the electrons, maybe the size of tiny BB’s, would be constantly flying around at speeds approaching the speed of light through the electron cloud in their orbitals.

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What are the parts of an atom?

•Technically, We Are 99.9% Empty Space?

• Why do we appear solid?

•Why Do Things Feel Solid?

We actually feel very little that is solid.What we feel is the interpretation of what solid is because of the electron clouds pushing away from one another.Which segues into the next part of the lesson.

•How Is an Atom Built?• Find carbon on the periodic table.• This is the information for the element CARBON• Notice its row and column.

• Every box represents a different element.• An element is any quantity of a substance that is 100%

the same type of atom.• Being the same type means they have the same # of

protons. • Ex: Diamonds are always the element carbon, regardless of the

size, because every atom has 6 protons.

• The six highlighted below are the most abundant elements in the bodies of most biological organisms.

• Take out the periodic tables & Mark these in your Periodic Table.

•CHNOPS: What are the Most Abundant Elements in Biology?

•Reading the Periodic Table• Atomic Number• Symbol• Name• Atomic Mass

•Atomic Numbers, Mass, Electrons…• The boxes give a lot of information.• How do you know how many protons, electrons, and neutrons an element has?

• It’s all based upon the atomic number found in the periodic table.

• Atomic # = # protons • # electrons = # protons• # neutrons = atomic mass - # protons.

•What Happens When an Atom Gains or loses an Electron is Ionic.• Rarely are atoms completely happy.• They are usually flying around or bouncing off on

another interacting with each other.• When this happens electron clouds interact.• Sometimes electrons will transfer between atoms in

this interaction.• When than happens is the electron-proton numbers

don’t match anymore. • This forms ions.• Ions are atoms that have a charge because the

proton-electron numbers don’t match.

•Formation of Ions: Count the p+ & e- before & after the exchange…

Sodium Before After Chlorine Before After

Protons +11 +11 Protons +17 +17

Electrons -11 -10 Electrons -17 -18

Total 0 +1 Total 0 -1

Na+ Cl-

Cation:A positively charged ion.

Anion:A negatively charged ion.

•Special Circumstance: IsotopesElements• Recall, elements are all the same type of atom because

every atom has the same number of protons.• For example, every atom for any amount of the element

carbon has six protons.• There are several types of carbon though.

• Atoms of an element can have different numbers of neutrons.

• Isotopes are atoms of elements that have a different number of neutrons.

• Isotopes create challenges and benefits because bonds form differently and are usually radioactive to a degree.

•Isotopes• Because Isotope atoms have the same number of protons, and also electrons, isotopes have the same chemical properties.

•The Numbers Really Matter• The numbers represent an atom’s proton, neutron, and electron number when it is un-bounded and electrically neutral.

• Atoms are rarely like this, stable, in nature.• Mainly because the electrons are always flying around.

electron

•Bohr’s V. Rutherford’s

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Different OrbitsSame Orbit

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•Where electrons actually are…Schrödinger• Q: Can you

identify where the electron is?

• A: No! because the electrons never stop moving!

•The Energy Levels• Atoms are usually represented as a nucleus surrounded by rings.

• The rings are energy levels.• The row (going from top to bottom) tells you how many rings the atom has.

• Hydrogen is in the 1st row = one ring• Nitrogen is in the 2nd row = two rings

• Shown to the right.

• These are the atom’s energy levels.

•Reading the Periodic Table• The Column tells you how many electrons in the outer shell (valence electrons).

• The Row tells you how many rings (Energy levels)

•The Outer Ring… The Valence Shell• Remember, electrons are orbiting the nucleus in the

region called the electron cloud... In different energy levels (orbitals).

• The outer ring is the important one. • It is the valence shell• This shows you the valence shell electrons.• In the valence shell bonding happens.

•The Outer Ring

• The column determines the valence shell electrons.

• Group 1A (hydrogen, etc.) has one valence electron.

• Group 2A (beryllium, etc.) has two.• This rule only applies to A groups though.

• The outer most edges of this cloud is called the valence shell.

• There is a strict rule for how many electrons are in this valence shell.

• For most groups of atoms, you can determine the # of valence shell electrons from the column it’s in.

•Concept Check• On your handouts (back side of the periodic table), complete the blank atom for the element carbon.

• Draw the:• Correct # of electrons• Correct # of electron in the valence shell• Correct # of protons• Correct # of neutrons

• Put them in the correct places.

•Atomic Models• There are a variety of ways to represent an atom…• It really depends on why you are showing the atom that will determine how you show it.

• Electron-Dot Diagrams = show electrons & protons for ions & bonding

• Space filling models = show how the molecule looks in 3D

• Bohr’s model = shows all electrons to represent energy levels. WHAT YOU BUILT

• Lewis structures = shows valence electrons (only) for bonding

•Lots of Atoms

• Which one’s right?

•How to Represent an Atom.• Standard Electron Dot Diagram.• Space-filling (O2)

• Bohr’s Model• Lewis Structure

•Group Section Questions: Answer these questions together as a group. Answers only. You have 10 minutes. We will cover these answers together at the end of class.

1. A(n) _________ is the smallest unit of matter that cannot be broken down by chemical means.

2. Identify the 3 sub atomic particles of atoms and their locations in words or in an illustration.

3. A(n) _________ is a substance made of only one kind of atom that has the same number of protons.

4. Locate oxygen and tell me how many protons, neutrons, and electrons it has. (use your periodic table…the atomic number is extremely useful).

5. Atoms are most stable when they have 8 electrons in their ______ ______.6. How many protons, electrons, neutrons, energy levels, and valence electrons

does carbon have?7. Name two ways that atoms can form bonds (combine to become more stable).8. Describe polarity and a popular polar molecule.9. Explain how polarity can cause salt & sugar to dissolve in water.10. Water is an example of a compound that is held together by ________ bonds.11. Atoms gain or lose ___________ to form ions.12. The opposite ends of a polar molecule have ___________ charges.13. A(n) _______ ______ is a weak chemical attraction between polar molecules.

1. A(n) _________ is the smallest unit of matter that cannot be broken down by chemical means.

2. Identify the 3 sub atomic particles of atoms and their locations in words or in an illustration.

3. A(n) _________ is a substance made of only one kind of atom that has the same number of protons.

4. Locate oxygen and tell me how many protons, neutrons, and electrons it has. (use your periodic table…the atomic number is extremely useful).

5. Atoms are most stable when they have 8 electrons in their __________ _________.6. How many protons, electrons, neutrons, energy levels, and valence electrons

does carbon have?7. Name two ways that atoms can form bonds (combine to become more stable).8. Describe polarity and a popular polar molecule.9. Explain how polarity can cause salt & sugar to dissolve in water.10. Water is an example of a compound that is held together by ___________ bonds.11. Atoms gain or lose _______________ to form ions.12. The opposite ends of a polar molecule have ___________ charges.13. A(n) __________ _________ is a weak chemical attraction between polar molecules.

atom

p+, e-, n0… p+, n0 in nucleus, e- in electron cloudelement

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shellvalence6 6 6 2 4

Ionic (swapping electrons), covalent (sharing electrons) When a molecule has a partial + & partial – charge. Water is polar and can dissolve the ions & polar molecules in sugar & salt

because of polarity.

covalent

electronsopposite

bondhydrogen

•Group Section Questions: Answer these questions together as a group. Answers only. You have 10 minutes. We will cover these answers together at the end of class.

•In-class Exercise: Check For Understanding

• To check that you’ve been paying attention and you understand

• Build a Phosphorus Atom1. Find the atom on the periodic table

2. Determine the number of protons, electrons, & neutrons.

3. Determine the energy levels.

4. Fill in the electrons, protons, & neutrons.

• Illustrate the Ionic Bond of NaCl• Illustrate the compound H2O• Show hydrogen bonding between 2 H2O molecules

n0 = 15p+ = 15

•Section Questions: Answer these questions in your notebooks. Write complete sentences for them all.

Section 2.11.A(n) _________ is the smallest unit of matter that cannot be broken down by chemical means.2.Identify the parts (particles) of atoms and their locations in words or in an illustration.3.A(n) _________ is a substance made of only one kind of atom that has the same number of protons.4.Name one element & how many protons, neutrons, and electrons it has. (use the back of the book for reference…the atomic number is extremely useful).5.Atoms are most stable when they have eight electrons in their _________ _________.6.How many protons, electrons, neutrons, energy levels, and valence electrons does carbon have?7.Name two ways that atoms can form bonds (combine to become more stable).8.Explain how charges cause salt & sugar to dissolve in water.9.Water is an example of a compound that is held together by _____ bonds.10.Atoms gain or lose ________________ to form ions.11.The opposite ends of a polar molecule have _____________ charges.12.A(n) ___________ ___________ is a weak chemical attraction between polar molecules.Section 2.2List & describe the 4 properties of water that make life on Earth possible.An example of a substance that heats more slowly than many other substances is ______.Why does water float?An attraction between particles of the same substance is called_______, while an attraction between particles of different substances is called ________.Differentiate between acids & bases.A solution that contains more hydronium ions than hydroxide ions is ____ and has a pH below _____.What is a buffer & what is it’s role in maintaining homeostasis?

•Summary• All matter is made up of atoms. An atom has a positively

charged nucleus surrounded by a negatively charged electron cloud.

• Chemical bonds form between groups of atoms because most atoms became stable when they have eight electrons in the valence shell.

• Polar attractions and hydrogen bonds are forces that play an important role in many of the molecules that make up living things.

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