1. LET’S STUDY FOR BENCHMARK EXAM #2!!!

2. S8P1A – DISTINGUISH BETWEEN ATOMS AND MOLECULES Atom = The smallest particle of an element; composed of a nucleus (which contains the protons and neutrons) and electrons circling the nucleus on energy fields The subscript in the chemical formula states the number of atoms of a particular element in that formula Example = H 2 O; the number 2 lets us know that there are 2 atoms of hydrogen in water Molecule = A combination of two or more atoms that are bonded together (examples include N 2, H 2, and H 2 O) The coefficient in front of a chemical formula states the number of molecules you have Example = 4H 2 O; the number 4 lets us know that there are 4 molecules of water H 2 O has a total of 3 atoms, 2 elements, and is one molecule (because there is no coefficient)

3. S8P1B – DESCRIBE THE DIFFERENCE BETWEEN PURE SUBSTANCES (ELEMENTS AND COMPOUNDS) AND MIXTURES Elements and compounds are pure substances Pure substances = A substance that is made of only one type of atom or molecule Elements = A substance that cannot be broken down into other substances by chemical or physical means; examples include gold, carbon, copper, silver, oxygen, boron, and nitrogen Compounds = A substance made of two or more elements chemically combined; examples include table salt, table sugar, and water Mixtures = Two or more substances that are mixed together but not chemically combined; examples include ice cream, kool aid, pizza, and milk

4. PROPERTIES OF MIXTURES AND COMPOUNDS Properties of Mixtures – The composition of a mixture is variable (it changes). – Each of its components retains its characteristic properties. – Its components are easily separated. Properties of Compounds – The relative proportions of the elements in a compound are fixed (it does not change). – The components of a compound do not retain their individual properties. Both sodium and chlorine are poisonous; their compound, table salt - NaCl - is absolutely essential to life. – It takes large inputs of energy to separate the components of a compound.

5. S8P1C – DESCRIBE THE MOVEMENT OF PARTICLES IN SOLIDS, LIQUIDS, GASES, AND PLASMAS STATES Solids = A state of matter with a definite shape and volume The particles in solids are packed tightly together and stay in fixed positions (the particles are still moving, but it is extremely slow) Liquids = A state of matter that has a definite volume but no definite shape The particles in liquids move around one another freely and take the shape of whatever container it is poured into (particles move faster than a solid, but slower than a gas) Gases = A state of matter with no definite shape or volume The particles in gases spread apart, filling all the space available to them (particles move fast) Plasmas = A state of matter in which atoms are stripped of their electrons and the nuclei are packed closely together

6. S8P1D – DISTINGUISH BETWEEN PHYSICAL AND CHEMICAL PROPERTIES OF MATTER AS PHYSICAL OR CHEMICAL Physical properties = Characteristics of matter – such as color, shape, taste, and density – that can be detected by the senses without changing the identity of the matter. Examples = Melting point, boiling point, density, color, shape, size To determine the density of an object, you need to divide the mass by the volume of that object Chemical properties = Characteristics of something that permits it to change into something else Examples = reactivity ( how something reacts with something else), combustibility (how something reacts with oxygen), flammability (how something burns), and whether it is an acid or a base (its pH)

7. S8P1E – DISTINGUISH BETWEEN CHANGES IN MATTER AS PHYSICAL OR CHEMICAL Chemical changes = A change in matter that produces new substances; examples include burning a match, the rusting of a bike, tarnish on silver, and place an alka seltzer tablet into water Signs that a chemical change has taken place include color change (that can not be reversed – like a leaf changing colors), a precipitate (combining two liquids and making a solid), gas production (like the smoke from burning a match), changes in properties (like flour, eggs, butter, etc. changing into cake), and changes in temperature (like the match being hot after it has been struck) Physical changes = A change that alters the form or appearance of a substance but does not make the material into another substance; examples include tearing paper into pieces, cutting wood, and melting ice into water

8. S8P1F – RECOGNIZE THAT THERE ARE MORE THAN 100 ELEMENTS AND SOME HAVE SIMILAR PROPERTIES Periodic Table = An arrangement of the elements in order of atomic number, in which elements with similar properties are grouped in columns There are approximately 112 elements on the periodic table Groups (Families) = Elements in the same vertical column of the periodic table; elements in the same group (family) have similar properties and have the same number of valence electrons (same number of electrons on the outermost energy level) Periods = A horizontal (left to right) row on the periodic table; elements in the same period have the same number of energy levels (i.e elements that has 1 energy level are in the same period)

9. S8P1G – IDENTIFY AND DEMONSTRATE THE LAW OF CONSERVATION OF MATTER Law of Conservation of Matter = States that matter is not created or destroyed but only changes its form Sample of the Law of Conservation of Matter: K + AgCl → KCl + Ag This is NOT a sample of the Law of Conservation of Matter: Na + CuS → Na2S + 2 Cu - WHY? It does not have the same number of atoms of each element on both sides The total quantity of matter and energy available in the universe is a fixed amount and never any more or less.

10. S8P2A – EXPLAIN ENERGY TRANSFORMATION IN TERMS OF THE LAW OF CONSERVATION OF ENERGY Law of Conservation of Energy = The rule that energy cannot be created or destroyed There is the same amount of energy today as there was at the beginning of time = the total amount of energy is constant Energy Transformations (Energy Conversions) = The process of changing one form of energy into another Examples of Energy Transformations: – Windmill = mechanical to electrical – Battery = chemical to electrical – Eating = chemical to mechanical or chemical or potential

11. S8P2B – EXPLAIN THE RELATIONSHIP BETWEEN POTENTIAL AND KINETIC ENERGY Potential Energy = Energy that is stored and held in readiness The higher an object is, the more potential energy it contains The heavier an object is, the more potential energy it contains Example = On the top of the highest hill of the roller coaster, the roller coaster has the most potential energy Kinetic Energy = Energy that an object has because of its motion Kinetic energy is also known as the energy of motion Something has to be moving in order for it to have kinetic energy Example = A ball falling, a car rolling, and an arm moving

12. S8P2C – COMPARE AND CONTRAST THE DIFFERENT FORMS OF ENERGY AND THEIR CHARACTERISTICS Heat (Thermal) = The total energy of the moving particles in an object Light (Radiant or Electromagnetic) = Energy that travels in the form of waves that have both electrical and magnetic properties Electrical = Energy from moving electric charges Chemical = Energy stored in chemical bonds Mechanical = Energy associated with the motion or position of an object Sound = Energy caused by an object’s vibrations

13. S8P2D – DESCRIBE HOW HEAT CAN BE TRANSFERRED BY RADIATION, CONDUCTION, AND CONVECTION Radiation = The transfer of energy by electromagnetic waves Example = the sun’s rays, the heat from a stove if you were to put your hand over it Conduction = The transfer of thermal energy between two particles within a substance; the transfer of electrons from a charged object to another charged object Example = your feet burning from hot concrete, a metal spoon’s handle warming from being in hot water, warm hands touching your face Convection = The transfer of thermal energy by the movement of currents within a liquid or gas Example = upstairs being warmer than downstairs, boiling water, wind

14. 4A - IDENTIFY THE CHARACTERISTICS OF ELECTROMAGNETIC AND MECHANICAL WAVES Mechanical waves need matter to transfer energy, while electromagnetic waves do not- they can travel through space, or a vacuum. Electromagnetic waves include the electromagnetic spectrum... (This includes visible light, radio waves, gamma rays, x-rays, ultraviolet rays, infra-red waves, and microwaves.) They both are able to travel through a medium of gas, liquid, or solid.

15. 4B - DESCRIBE HOW THE BEHAVIOR OF LIGHT WAVES IS MANIPULATED CAUSING REFLECTION, REFRACTION, DIFFRACTION, AND ABSORPTION Waves that meet each other or an object in the environment may interact. There are several types of interactions that waves may have. Reflection occurs when a wave bounces back after striking a barrier. Reflected sound waves are called echoes; reflected light waves allow us to see objects. Refraction is the bending of a wave as it passes at an angle from one medium to another. One common example of refraction of light waves is the broken pencil effect that can be observed when a pencil is placed in a glass of water. The pencil seems to be "broken" at the surface of the water as the light waves go from the air to the water. Diffraction is the bending of waves around a barrier or through an opening. The amount of diffraction a wave experiences depends on two factors: the wavelength of the wave and the size of the barrier or opening the wave encounters. Sound travels around corners because it has relatively larger wavelengths than light. We can hear sounds around corners. We can't see around corners because light has a very small wavelength.

16. 4C - EXPLAIN HOW THE HUMAN EYE SEES OBJECTS AND COLORS IN TERMS OF WAVELENGTHS

17. 4D - DESCRIBE HOW THE BEHAVIOR OF WAVES IS AFFECTED BY MEDIUM (SUCH AS AIR, WATER, SOLIDS) Waves either speed up or slow down in different mediums (air, water, solids) Sound travels fastest in solids and slowest in gases Speed of light is only constant in vacuums (and it goes fastest in vacuums) The speed of light is so slight in other mediums that it is unnoticeable

18. 4E - RELATE THE PROPERTIES OF SOUND TO EVERYDAY EXPERIENCES

19. 4F - DIAGRAM THE PARTS OF THE WAVE AND EXPLAIN HOW THE PARTS ARE AFFECTED BY CHANGES IN AMPLITUDE AND PITCH The amplitude of a wave is the maximum distance the wave vibrates from its rest position. The rest position of a wave is where the particles of a medium stay when there are no disturbances. The larger the amplitude, the greater is the energy of the wave. Wavelength is the distance between two adjacent crests or compressions in a wave. Therefore wavelength is the distance from any point on a wave to the corresponding point on the next wave. Frequency is the number of waves produced in a given amount of time. Frequency can be measured by counting either the number of crests or the number of troughs that pass a point in a certain amount of time. Frequency is expressed in hertz (Hz). Higher frequency, just like higher amplitude, means more energy. Wave speed is the speed at which a wave travels. The speed of a wave depends on the medium in which the wave is traveling. Sound waves travel fastest in solids, next fastest in liquids, and slowest in gases. Wave speed can be calculated by multiplying the wavelength (represented with the Greek letter lambda) times the frequency of the wave.

20. 5B - DEMONSTRATE THE ADVANTAGES AND DISADVANTAGES OF SERIES AND PARALLEL CIRCUITS AND HOW THEY TRANSFER ENERGY An advantage to parallel circuits is that if one component fails the circuit is not broken, therefore allowing the rest of the components to receive electricity. A good example of this is a string of Christmas lights which are wired in parallel so that if one bulb blows the entire circuit is not broken. What is arguably the major disadvantage of a parallel circuit is that as you add more and more things in parallel, the current draw on the source goes up and up and up. If the source cannot supply the current that is "demanded" by the devices all strapped across the so-called "rails" of the circuit, the voltage will (must!) decrease. This could be very bad, as some devices, notably motors, don't like to run at low voltage and can actually be damaged if voltage sags too much and they don't have undervoltage protection