8th Chemistry Final

Question 1

What is a Proton?

Answer 1

A proton has a positive charge and is located in the nucleus

Question 2

What is a Neutron?

Answer 2

A Neutron has a neutral charge and is located in the nucleus.

Question 3

What is an electron?

Answer 3

An electron has a negative charge and is located in the electron cloud.

Question 4

How is the periodic table organized?

Answer 4

By groups, atomic number, periods. Metals, transition metals, and nonmetals.

Question 5

What elements make an ionic bond? What charge?

Answer 5

Metals and nonmetals. One cation and one anion.

Question 6

What holds together bonds?

Answer 6

An attractive force.

Question 7

What elements make a covalent bond? What charge?

Answer 7

Nonmetals and nonmetals. A neutral charge.

Question 8

What happens when an element loses all of its valence electrons?

Answer 8

It becomes a cation.

Question 9

What are some examples of chemical changes?

Answer 9

Combustion, digestion, rusting, precipitate.

Question 10

What happens during a chemical reaction?

Answer 10

Bonds between atoms break and form to create new substances.

Question 11

What are some indications that a chemical change has taken place?

Answer 11

Temperature change, precipitate, change in color, and bubbles forming.

Question 12

What are some examples of physical changes?

Answer 12

Cutting vegetables, boiling water, and dissolving.

Question 13

What is a physical property?

Answer 13

A characteristic of a substance that is observed without changing the chemical makeup of the substance.

Question 14

What are some examples of physical properties?

Answer 14

Density, conductivity, melting point, and temperature.

Question 15

What are three physical properties of water?

Answer 15

Solid (ice), liquid (water), gas (vapor).

Question 16

What are some indications that a physical change has taken place?

Answer 16

Change in size, shape, form, or phase. The substance is the same as before.

Question 17

What does the law of conservation of mass state? Why is it important in chemical reactions?

Answer 17

Mass in chemical reactions is neither created nor destroyed. It is important to understand when balancing chemical equations.

Question 18

What does the law of conservation of energy state? Why is it important to understand in chemical reactions?

Answer 18

Energy in a chemical reaction is neither created nor destroyed. It explains how energy changes forms and is transferred into new substances.

Question 19

What are the two components in chemical reactions?

Answer 19

Reactants and products.

Question 20

What are some examples of chemical properties?

Answer 20

Flammability, Reactivity, heat of combustion, toxitity, acidity.

Question 21

What is the difference between a coefficient and a subscript?

Answer 21

Coefficients tell how many molecules there are. Subscripts tell how many of each atoms there are.

Question 22

Why is dissolving a physical change?

Answer 22

It changes the physical feature of the substance, not the chemical make up of the substance. It can be reversed.

Question 23

What happens to the reactants and products when a heat pack is broken and releases heat?

Answer 23

It conducts an exothermic process and releases more energy when the bonds of the products are formed than when the reactants bonds are broken.

Question 24

What are endothermic and exothermic reactions? What happens to the energy in each case?

Answer 24

Exothermic reactions release energy. More energy in reactants than products. Endothermic reactions absorb energy. More energy in products than reactants.

Question 25

What are some examples of endothermic reactions?

Answer 25

Cold packs, photosynthesis, dissolving of ionic salt, decomposition of water, and evaporation.

Question 26

What are some examples of exothermic reactions?

Answer 26

Hot packs, fireworks, respiration, rusting, candle burning, and freezing.