Chemistry Review

Question 1

According to the law of conservation of matter, what is true in ALL CHEMICAL REACTIONS?

Answer 1

Atoms are NEVER CREATED OR DESTROYED, but only rearranged.

Question 2

What are the three parts of an atom?

Answer 2

1. Protons (positive, inside nucleus)
2. Electrons (negative, float outside AROUND nucleus and PARTICIPATE IN CHEMICAL REACTIONS)
3. Neutrons (neutral charge, inside nucleus)

Question 3

Define compound.

Answer 3

The chemical combination of two or more atoms.

Question 4

The substance USED in a chemical reaction is a ____________.

Answer 4

Reactant

Question 5

The substance CREATED in a chemical reaction is a _____________.

Answer 5

Product

Question 6

Explain the difference between a gas and a liquid.

Answer 6

Gases AND liquids have “indefinite shapes” (meaning they can take the shape of whatever container they are in), but ONLY GASES have an indefinite VOLUME as well (liquid will take up the same AMOUNT OF SPACE regardless of what container it is in).

Question 7

H2O has how many of what atoms?

Answer 7

Two hydrogens and one oxygen.

Question 8

Compare between a compound and its component elements.

Answer 8

1. The PHYSICAL properties of a compound are DIFFERENT than the elements that compose it.
2. The CHEMICAL properties of a compound are DIFFERENT than the elements that compose it.

Question 9

What does it mean to “compress” something?

Answer 9

Squish it together, like squeezing a pillow to make it smaller.

Question 10

Why are liquids harder to compress than gases?

Answer 10

Because gases have more empty space between each molecule.

Question 11

What are the most common elements in living things?

Answer 11

C, N, O, H, P, and S