Chemical Reactions

Question 1

valence electrons determines3

Answer 1

• how reactive element is
• hat elements it will react with
• either lose or gain to form bonds

Question 2

lewis structure

Answer 2

shows only valence electrons

Question 3

chemical bond2

Answer 3

• force of attraction that holds 2 atoms together

- held together by negative and positive charges

Question 4

ion

Answer 4

-atom that has electric charge

Question 5

cation2

Answer 5

• positive

- loses electron

Question 6

anion2

Answer 6

• negative

- gains electron

Question 7

polyatomic ion2

Answer 7

• made of more than one atom

- can be positive or negative

Question 8

ionic bond6

Answer 8

• when atoms gain or lose valence electrons
• opposites attract, + and - hold it together
• occur between metals (left) and nonmetals (right)
• intend to attain a gull outer shell (2 or 8)
• atoms with 1-4 v.e. will lose
• atoms with 4-7 v.e. will gain

Question 9

oxidation number3

Answer 9

• the electric charge an atom has after it gains/loses electrons
• charges balance each other (should equal 0)
• little - or + in top after chemical symbol

Question 10

subscripts2

Answer 10

• ratio of elements in compound

- little number in bottom after chemical symbol

Question 11

coefficients2

Answer 11

• amount of a compound present

- big number before chemical symbol

Question 12

covalent bond4

Answer 12

• when 2 atoms share electrons
• formed between atoms of nonmetals
• share electrons to get a full outer shell
• number of bonds on atom can form equals number of electrons needed to make 8

Question 13

double bond

Answer 13

atoms share 2 pairs of electrons

Question 14

triple bond

Answer 14

atoms share 3 pairs of electrons

Question 15

molecular compound3

Answer 15

• composed of covalent bonds
• low melting points
• do not conduct electricity

Question 16

polar bond3

Answer 16

• some atoms pull more strongly on shared electrons
• makes one side more negative and other more positive
• why water sticks together

Question 17

non polar bonds2

Answer 17

• shared electrons pulled equally

- no charge on either side

Question 18

reactant

Answer 18

atom or molecule that go into a chemical reaction and interact (left side of equation)

Question 19

product

Answer 19

new atoms and molecules that are produced from a chemical reaction (right side of equation)

Question 20

precipitate

Answer 20

a product of chemical reaction that is a soild

Question 21

evidence for chemical reactions4

Answer 21

• color change
• solid (precipitate) appears
• gas appears
• change in energy

Question 22

exothermic reaction3

Answer 22

• releases heat
• temp increases because releases thermal energy
• small arrow, big arrow

Question 23

endothermic reaction3

Answer 23

• absorbs heat
• temp decreases because thermal energy turns into chemical energy
• big arrow, small arrow

Question 24

activation energy

Answer 24

minimum amount of energy needed to start a chemical reaction

Question 25

controlling chem reactions using surface area

Answer 25

when solid is broken into smaller pieces, reaction happens faster

Question 26

controlling chem reactions using temperature

Answer 26

when temperature increases, reaction happens faster

Question 27

controlling chem reactions using concentration

Answer 27

when there is more concentration (amount of a substance in a given volume), reaction happens slower because there are more particles to reaction. product may also be different

Question 28

controlling chem reactions using catalysts

Answer 28

when there are more catalysts (material that lowers activation energy), increases rate of reaction

Question 29

controlling chem reactions using inhibitors

Answer 29

when there are more inhibitors, reaction happens slower | Ex: food preservatives

Question 30

synthesis2

Answer 30

to put together | a+b--> ab

Question 31

decomposition2

Answer 31

to break apart | ab-->a+b

Question 32

single replacement2

Answer 32

to take place of | ab+c-->a+bc

Question 33

double replacement2

Answer 33

to trade places | ab+cd-->ac+bd

Question 34

diff between coefficients and subscripts

Answer 34

coefficients can be changed, subscripts can't