People Search for Review

People Search for Review KEY

1. What is the difference between a mixture and a compound? Give an example of each. A compound is a substance that is made up of two or more elements that are chemically combined. An example of a compound is H2O (water). A mixture is a substance that is made of two or more elements or compounds and not chemically combined – thus separable. An example would be lemonade.

2. Describe a proton. Why are electrons ignored when finding the mass of an atom? Where are each of the subatomic particles found in an atom? A proton is a subatomic particle that has a positive charge and it is found in the nucleus. Electrons are ignored when calculating mass because they are so small in mass. Electrons have a negative charge and are found in energy levels outside the nucleus. Neutrons have no charge and are found in the nucleus.

3. What determines if an atom is an ion or not? Draw a Bohr model of an ion of helium.

An ion is an atom that has unequal numbers of protons and electrons. (A Bohr model of an ion of helium would have two protons, zero or more neutrons, and – because it is an ion, it cannot have two electrons – zero or one electrons.)

4. What is an isotope? What makes an isotope of one element different from a different isotope of the same element?

Isotopes are atoms of a particular element that has different numbers of neutrons. The two isotopes would have different numbers of neutrons but the same numbers of protons (or else they wouldn’t be the same element).

5. Describe the arrangement of atoms in a solid, liquid and a gas of a substance. Rank the states of matter in order of highest energy to lowest energy.

Solids have the lowest amount of energy, while a liquid would have the second lowest amount of energy. Gas would have the second highest amount and plasma would have the most energy. 6. Describe what happens to the molecules of air in a hot air balloon in terms of a) pressure; b) density; c) motion; and d) number of collisions when the balloonist heats the air.

When the air is heated, the air particles will undergo an increase in pressure, a decrease in density, an increase in motion and an increase in the number of collisions.

7. What happens to the energy of particles as they are heated? What happens to temperature of the particles?

The energy of the particles increase as they are heated. The temperature of the particles increase

8. Sketch a phase diagram for water. Label the graph where the water is a) liquid; b) solid; c) gas; d) melting; e) boiling.

(The graph above has temperature on the Y axis and Time on the X axis.) A = solid state; B to C = melts; C to D = liquid state; D to E = boiling; E to F = gas

Sign for 3 problems which you feel confident in completing.

1. ______5. ______

2. ______6. ______

3. ______7. ______

4. ______8. ______