Physical Science: This section makes up 30% of the HSPE.

~18 questions

Topics of Physical Science

• 1. Matter• 2. Force and Motion• 3. Energy

Matter• Matter is anything that has mass and takes up space.

• The physical forms of matter, either solid, liquid, or gas, are called the states of matter.

• Solids are a form of matter that have their own definite shape and volume.

• Liquids are a form of matter that have a definite volume but take the shape of the container.

• Gases have no definite shape or volume. They expand to fill their container.

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Sample Question

• Which of the following correctly describes the motion of particles in a gas? – They do not move at all. – They move rapidly around in random patterns. – They vibrate in a set pattern. – They flow easily, but slowly around each other.

Atomic Number• Each element contains a unique positive charge in their

nucleus.

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Atomic Number: # protons and electrons

Atomic mass: # protons + # neutrons

Trends of the Periodic Table

• Increasing atomic number and mass across and down.

• Columns of elements are called groups.• Rows of elements are called periods.• Groups have the same properties, and # of

valence electrons

The shape of the periodic table becomes clear if it is divided into blocks representing the atom’s energy sublevel being filled with valence electrons.

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Sample Question

• What is common among a family of elements?– Number of valence electrons.– Number of energy levels.– Shielding effect of electrons.– Amount of protons in the nucleus.

PropertiesElements are classified as metals, non-metals, and

metalloids.Metals are elements that are generally shiny (luster) when

smooth and clean, solid at room temperature, and good conductors of heat and electricity.

Non-metals are elements that are generally gases or brittle, dull-looking solids, and poor conductors of heat and electricity.

Metalloids have physical and chemical properties of both metals and non-metals, such as silicon and germanium.

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Sample Question

• Which of the following are properties of metals?– Malleable, ductile, and good conductors of heat and

electricity.– Malleable, dull, and good conductors of heat and

electricity.– Ductile, shiny, and poor conductors of heat and

electricity.– Ductile, malleable, and poor conductors of heat and

electricity.

Mixtures• A mixture is a combination of two or more pure

substances in which each pure substance retains its individual chemical properties.

• A homogenous mixture is a mixture where the composition is constant throughout.

• Homogeneous mixtures are also called solutions

• A heterogeneous mixture is a mixture where the individual substances remain distinct.

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• Mixtures– can have the same composition throughout.– have physical properties dependent on its

components.– have the same physical properties as compounds.– cannot be separated into their components.

Separating Mixtures• Filtration is a technique that uses a porous barrier to separate a solid

from a liquid in a heterogeneous mixture.

• Distillation is a separation technique for homogeneous mixtures that is based on the differences in boiling points of substances.

• Crystallization is a separation technique for homogenous mixtures that results in the formation of pure solid particles from a solution containing the dissolved substance.

• Chromatography is a technique that separates the components of a mixture on the basis of tendency of each to travel across the surface of another material.

• Sublimation is the process of a solid changing directly to a gas, which can be used to separate mixtures of solids when one sublimates and the other does not.

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Sample Question

• Which of the following contains a homogeneous mixture?

• Sample A• Sample B• Sample C• Sample D

The Atom• The smallest particle of an element that retains the

properties of the element is called an atom.• Atoms are made of Protons, Neutrons, and electrons. • Protons and Neutrons are in the nucleus and electrons

are outside the atom.

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Elements and Compounds

• A compound is a made up of two or more elements combined chemically.

• Elements can never be separated• Compounds can be broken into components

by chemical means

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Isotopes• Atoms with the same number of protons but

different numbers of neutrons are called isotopes.

• The mass number is the sum of the protons and neutrons in the

nucleus.• Calculating Protons, neutrons

and electrons: – Mass #-Atomic number=neutrons– Atomic # is protons and electrons

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Sample Question

• The nucleus of an atom consists of protons and neutrons. In an isotope thenumbers of – protons vary.– neutrons vary.– electrons vary.– quarks vary.

Sample Question

• Atoms of a certain isotope have 73 neutrons and a mass number of 123. What is its atomic number?– 73– 123– 196– 50

IonsAn ion is an atom or bonded group of

atoms with a positive or negative charge. Metals are cations (positive charge), they lose

electrons. Non-metals are anions (negative charge, they

gain electrons

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Sample Question• Lithium releases an electron to fluorine to form the compound lithium

fluoride. Analyze the model of this ionic bonding shown in the diagram below.

• Which of the above electron transfers correctly models the bonding arrangement between lithium and fluorine to form lithium fluoride?– I only– II only– III only– I and II

Conservation of Mass

• The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction, it is conserved.

• The mass of the reactants equals the mass of the products.

massreactants = massproducts

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Valence Electrons and Chemical Bonds• A chemical bond is the force that holds two atoms

together.

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*Outside electrons are bonding electrons, called Valence Electrons.

Covalent bonds are bonds in which elements share electrons. They are non metals bound to other non metals.

Sample QuestionWhich of the following is true about the models?

• Model I shows ionic bonding because the valence electrons are shared.• Model II shows covalent bonding because the valence electrons are transferred.• Model I shows covalent bonding because the valence electrons are transferred.• Model II shows ionic bonding because one electron is transferred to another

atom.

Energy in Reactions• Reactions that absorb energy are endothermic.• Reactions that release energy are exothermic

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Photosynthesis, baking a cake, and cooking an egg are all examples of chemical reactions that absorb energy.

The burning of gasoline and cellular respiration are both chemical reactions that release energy

Reactions can sped up by a few different factors:

• Increasing concentration. With an increase in concentration, it is more likely that the atoms will come in contact with each other.

• Increasing the surface area of solids for example shredding or crushing. If you tried to build a fire, you would not start a fire with 2 big blocks of wood, you would chop the wood to increase surface area.

• Increasing the temperature. When you make tea, you boil the water to increase the speed that your tea packet dissolves into the water. In cold water, it would take tea significantly longer to dissolve.

• Adding a catalyst. These always speed up reactions. Yeast is the catalyst that is used when baking bread, it causes the bread to rise faster than bread made without yeast.

Sample Question

• Burning fuel, combining baking soda and vinegar, and decomposing water into hydrogen and oxygen are examples of chemical reactions. Which statement correctly identifies what occurs in all chemical reactions?– Matter is either created or destroyed.– Energy is either created or destroyed.– Matter is converted into energy.– Energy is transferred from one form to another.

Sample Question

• Photosynthesis, baking a cake, and cooking an egg are all examples of chemical reactions. Identify the statement that correctly identifies the role of energy in each of these reactions.– These reactions are exothermic or release heat.– These reactions are exothermic or absorb heat.– These reactions are endothermic or release heat.– These reactions are endothermic or absorb heat.

Part 2: Force and Motion

Force and Motion• Newton’s First Law states that an object at rest remains at

rest, and an object in motion continues in motion at a constant velocity in a straight line, unless acted upon by an external force or unbalanced force. An object resisting a change in its “natural state of motion” (stopped or moving in a straight line) is what Newton referred to as inertia.

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Force and Motion

• Newton’s Second Law states when an external, unbalanced force acts on an object, the object will accelerate in the same direction as the force. The acceleration varies directly as the force, and inversely as the mass.

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Force and Motion

• Newton’s Third Law states that for every action force, there is an equal and opposite reaction force. This law is also known as the Law of Action-Reaction.

• Athlete pushes bar (an action); the bar pushes athlete downwards (the reaction).

• The baseball forces the bat to the right (an action) the bat forces the ball to the left (the reaction).

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Sample Question

• Which of the following would require the least amount of force, if applied to the same ball?– Stopping the ball that is rolling on a flat and smooth

surface.– Changing the direction of a ball that is rolling on a flat

and smooth surface.– Starting the ball in motion on a flat and smooth

surface.– Keeping the ball moving at a constant speed on a flat

and smooth surface.

Sample Question

• Which of the following boxes would have the most friction acting upon it?– A smooth metal box being pushed across a smooth

wooden floor.– A smooth metal box being pushed across a rough

carpeted floor.– A rough cardboard box being pushed across a smooth

wooden floor.– A rough cardboard box being pushed across a rough

carpeted floor.

Part 3: Energy

Waves P.12.C.1

Electromagnetic Spectrum P.12.C.1

Sample Question

• Wave motion in a medium transfers– energy, but the matter vibrates around a fixed

point.– both mass and energy, in the direction of the

wave’s motion.– neither mass nor energy, both just vibrate.– mass, but the energy vibrates around a fixed

point.

Energy can only be transformed, not created…see below.

Kinetic= MotionPotential=No motion

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Sample Question• After a student stretches a rubber band many times, they

notice that the rubber band is now very warm to the touch. Which of the following predictions should be made?– The rubber band collected heat from the surrounding air after

continuous stretching.– The stretching transferred energy to the rubber band and some

of that energy was transferred to heating the rubber band. – The chemical reactions activated by the stretching caused an

increase in the rubber band’s temperature.– The rubber band must have been warm prior to stretching and

cooled somewhat during the stretching process.

Sample Question

• Energy is created as the result which activity?– Burning gasoline in an internal combustion engine.– Damming a river for hydroelectric power.– Rolling a marble down an incline plane.– Energy can only be transformed, not created.

Fission vs. Fusion• Nuclear FissionWhen nuclear fission occurs, an atom is split into one or more progeny products. In this reaction, some of the nuclear mass is converted to energy. With the large amounts of nuclei involved, a tremendous amount of energy is released.

Nuclear FusionWhen nuclear fusion occurs, two or more lighter elements combine to form a heavier atom.

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Sample Question

• Which of the following correctly describes how water is used to generate electricity?– Moving water turns a turbine which turns a

generator.– A turbine moves water which turns a generator.– A generator moves water to turn a turbine.– Still water enters a turbine which turns a

generator.

Electricity

At its most basic, an electrical circuit is a mechanism for transferring energy. As such, an electrical circuit must have the following components: (1) an energy source, (2) a closed path for energy transfer, and (3) an object where the energy is converted for use.

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Circuits

• Diagrams of simple series (right) and parallel (left) circuits. The top figures are cartoons showing the wires, switch,bulb, and battery.

• ***Electrons move from one side of the battery to the other.

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Sample Question

• What function does a circuit serve in your home?– It protects your home against lightning strikes.– It increases the voltage from the power lines

outside your house.– It provides a complete path through which

electrical energy can flow.– It provides a barrier against electromagnetic

radiation from the outside.