chapter 3 test

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Modern Chemistry
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1

antione-laurent de lavosier laid the foundation of chemical sciences by establishing the important laws of

chemical combinations

2

what did antoine-laurent de lavosier have a strong influence on?

histories of chemistry and biology

3

who established the law of conservation of mass

antoine l lavoiser

4

which law states "mass can neither be created nor destroyed in a chemical reaction"?

law of conservation of mass

5

the substances that combine or react are called

reactants

6

the new substance/substances formed are called

products

7

which law says " if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is a always a ratio"?

law of multiple proportions

8

h2o has a ratio of

2:1

9

h2o2 has a ratio of

2:2

10

which law says "a chemical compound always contains exactly the same proportions of elements by mass"

law of constant porportions

11

what is another name for the law of constant proportions?

law of definite proportions

12

who developed the atomic theory

john dalton

13

atoms of a given element are identical in

size, mass, and other properties

14

elements are made of extremelly small particles called

atoms

15

atoms cannot be

subdivided, created, or destroyed

16

atoms of different elements combine in what kind of ratios to form chemical compounds?

whole-number ratios

17

in chemical reactions, atoms are

combined, separated, or rearranged

18

all matter is composed of

atoms

19

atoms can be defined as the smallest particle of matter than can take part in what kind of reactions?

chemical

20

are atoms small?

yes, very very small

21

what charge do protons have

positive

22

if you change the number of protons, what happens?

you change the element

23

what charge do neutrons have

neutral. NO charge

24

what charge do electrons have

negative

25

if you change the number of electrons, what happens?

you change the charge

26

can atoms be seen with the naked eye?

no

27

do atoms exist in a free state in nature?

no, but they do take part in chemical reactions

28

the size of an atom is indicated by what

its radius

29

the mass of an atom is called what

atomic mass

30

the atomic number is equal to the number of _____ of each atom?

protons

31

the mass number is the total number of ____ and ____ added together

protons and neutrons

32

what are isotopes

atoms of the same element that have different masses

33

whats the most stable carbon isotope?

carbon 12

34

avogadro's number is what

6.022 x 1023

35

molecule definition

group of 2 or more atoms that are chemically bonded together, that is, tightly held together by attractive forces

36

when converting from g to moles, what do you do?

you out the given gram over 1 and multiply by 1 mol over the atomic(or molar) mass of the given

37

when converting from mol to mass, what do you do?

you put the given over 1 and multiply by the molar/atomic mass over 1 mol

38

when converting mol to atoms, what do you do?

you put the given over 1 and multiply by 6.022 x 1023 over 1

39

when converting from grams to mass, what do you do?

you put the given over 1 and multiply by 1 mol over the atomic mass and then multiply by 6.022 x 1023 over 1 mol

40

when converting from atoms to moles, what do you do?

you put the given over 1 and multiply by 1 mol over 6.022 x 1023