Atoms and Chemical Reactions

What has taken place in this picture

• a chemical reaction

• a physical change

• an exothermic reaction

• a chemical change

The total number of oxygen on each side of this chemical equation is

2H₂ + 0₂ ---> 2H₂0

• 2

• 1

• 4

In a chemical reaction, the reactants are on the left side?

• True

• False

In a chemical reaction, the products are on the right side.

• False

• True

Exothermic reactions are those that

• require energy to be supplied

• Always require heat in order to begin

• Never require heat in order to begin

• Give off heat after they begin

What factor can determine if a chemical reaction has occured?

• Can it be performed by another scientist?

• Can it be reversed?

• Does it have color?

• Can it be pounded into powder?

To find the number of neutrons in an atoms on the periodic table, you would...

• Multiply the atomic number by 2

• Calculate the number of electrons

• Subtract the atomic mass from the atomic number

• Subtract the number of Protons from the atomic mass

An atom with an atomic mass of 12 and an atomic number of 5 has how many neutrons?

• 7

• 5

• 12

• 17

What happens to the atomic number has you read left to right across the any period on the periodic table?

• Decreases

• remain the same

• Both increase and decrease

• Increase

Be and Mg have how many valence electrons?

• 1

• 4

• 2

• 16