Chemistry Unit Study guide Answers 1 Using the

Chemistry Unit Study guide Answers

1. Using the periodic table, locate the following elements – write down the atomic number and atomic mass and determine the number of protons neutrons and electrons • Selenium • Argon • Radon – – – 18 40 18 22 18 • Phosphorus – 15 – 31 – 15 – 16 – 15 – – – 34 79 34 45 34 • Uranium – – – 92 238 92 146 92 – 86 – 222 – 86 – 136 – 86

2. Draw a diagram that shows the molecules of a liquid, solid and gas in relation to each other. Describe the KE and motion in each state • Solid – low KE, particles only vibrate in place • liquid – higher KE, particles are able to move past each other somewhat, but are still bonded together • Gas – highest KE, particles are completely free of each other and spread apart quickly

3. a. Define density how much matter is found in a given space b. What are some units of density? g/cm 3, kg/m. L, mg/l c. Give two examples of how to determine volume measure (l x w x h) or water displacement e. How would you know if a substance was more dense than water? Less dense? if it is more dense it will sink in water; if it is less dense it will float on the water. Ex: golf ball vs ping pong ball

4. define: a. Matter: anything that has mass and takes up space b. Atom: the smallest stable piece of matter c. Proton: the large positive subatomic particle found in the nucleus d. Neutron: the large neutral subatomic particle found in the nucleus e. Electron: the small negatively charged subatomic particle found outside the nucleus e. Electron cloud: area around nucleus where electrons are found f. Nucleus: large positively centrally located part of the atom

5. A. What is the difference between temperature and heat? temp: average KE of all atoms in an object heat: the transfer of that energy between two objects with different temps B. How does energy move through heat? it moves from the high temp object to the lower temp object as their atoms collide c. Describe the movement of energy: 1. Dive into pool on hot day – your atoms transfer energy to the lower temp pool atoms 2. Come into class and feel cold – the room has a lower temp so your energy is transferred to the air 3. Touch a hot stove – the stove has a higher temp so it transfers energy to your skin, burning it

6. Describe each of the phase changes • • Melting – solid to liquid – energy is added Evaporating – liquid to gas – energy is added Condensing – gad to liquid– energy is released Freezing – liquid to solid – energy is released

7. Describe three types of heat transfer • Conduction : energy transfer through direct contact (atoms collide with each other) – Heating a pan to cook with, the contents of the pan heating up • Convection: energy transfer through a gas or liquid – Convection oven to cook (air travels around food), boiling water • Radiation: energy transfer using electromagnetic waves – Light waves, x rays, radio waves, microwaves