Chemistry Unit 2 Test

Front 1

how do you calculate percent composition?

Back 1

percentage = part/whole x100%

Front 2

how do you find the percentage of mass of a compound?

Back 2

% element = (number of atoms)(atomic weight)/(FW of the compound) x 100

Front 3

how do you calculate the empirical formula?

Back 3

1. change % to grams

2. change grams to moles

3. divide by the mole amount

4. multiply each # by the same integer to get whole #'s (clear fraction)

5. write formula with the proper subscripts

Front 4

Where are the protons location in the atom?

Back 4

in the nucleus

Front 5

Where is the mass/atomic number located in the writing of the complete atomic symbol?

Back 5

top left side of the element

Front 6

what is located at the bottom left side of the element in the complete atomic symbol?

Back 6

number of atoms

Front 7

what do you need in order to calculate the average atomic mass for an element?

Back 7

atomic mass of different isotopes and relative abundance

Front 8

what are chemical isotopes?

Back 8

atoms with same number of protons but different number of neutrons

Front 9

what the difference between a cation and an anion?

Back 9

cation is positive and anion is negative

Front 10

what are the 5 main points of dalton's atomic theory?

Back 10

1. all matter is composed of very small particles called atoms

2. atoms of an element are identical in size, mass etc.

3. atoms cannot be subdivided, created or destroyed

4. atoms are different elements combined in simple, whole number ratios to form chemical compounds

5. in chemical reactions, atoms are combined, seperated or rearranged

Front 11

what is an atom?

Back 11

smallest particle of an element that retains the chemical properties of that element

Front 12

what is an electron?

Back 12

negatively charged particles surrounding the nucleus

Front 13

what is a neutron?

Back 13

neutral particles found in nucleus with protons

Front 14

what is a proton

Back 14

positively charged particle found in nucleus with neutrons

Front 15

what is a nucleus?

Back 15

small region located at center of atom with protons and neutrons inside

Front 16

What did Thomson say about cathode rays?

Back 16

cathode rays must be composed of identical negatively charged particles named electrons

Front 17

What did Milkilan find?

Back 17

found measure of charge of the electron

Front 18

What did Rutherford find?

Back 18

volume of nucleus was very small compared with total value of atom; deflected alpha particles experienced some powerful force within the atom

Front 19

what is the atomic number?

Back 19

(z) number of protons of each atom of an element

Front 20

what is the mass number?

Back 20

total number of protons and neutrons that make up the nucleus of the isotope

Front 21

what is the relative atomic mass?

Back 21

one atom chosen as standard and assigned a mass value. Masses of other atoms are expressed by this standard

Front 22

What is the average atomic mass?

Back 22

Weighted average of the atomic masses of the naturally occurring isotopes of an element

Front 23

what is a mole?

Back 23

(mol) amount of a substance that contains as many particles as there are atoms in exactly 12g of carbon

Front 24

what is avagadro's number?

Back 24

6.022 x 10^23

Front 25

what is the molar mass?

Back 25

mass of one mole of a pure substance

Front 26

what is an isotope?

Back 26

atoms of same element with different masses

Front 27

what does the catharay experiment prove?

Back 27

1. found the first subatomic particle discovered (negatively charged)

2. discovered the electron

3. smaller than hydrogen

Front 28

What did the gold foil experiment prove?

Back 28

1. atoms were largely empty space

2. occassionally hit something and came back (hit nucleus)

3. small positive charge (nucleus)