chem chapter 3 test

Question 0

first to organize elements into a table was \_\_\_\_
how were (are) they organized

Answer 0

Dmitrie Mendeleev

increasing atomic mass

Question 1

Chemists have always used the _____ of the elements to sort them out

Answer 1

properties

Question 2

periods(rows) are _____ and there are ___ of them

groups(columns) are ____ and there are ____ of them

Answer 2

horizontal, 7

vertical, 18

Question 3

what are the 4 organizational patterns to the modern day period table

Answer 3

increasing atomic number, metals nonmetals and metalloids, periods and groups, blocks (spdf)

Question 4

what is the smallest particle of an element

Answer 4

atom

Question 5

who was the first to suggest that atoms existed

who developed the scientific theory behind atoms

Answer 5

democritus, dalton

Question 6

true or false

different atoms can never chemically combine in fixed ratios to form compounds

Answer 6

false

Question 7

true or false

atoms can never change their identity during chemical reactions. They can rearrange to form different compounds

Answer 7

true

Question 8

who conducted the gold fold experiment to discover protons

Answer 8

Rutherford

Question 9

positive charge, 1 amu (atomic mass unit), within the nucleus

Answer 9

proton

Question 10

no charge, 1 amu, within the nucleus

Answer 10

neutron

Question 11

negative charge, 1/1840th of a proton or neutron, outside the nucleus

Answer 11

electron

Question 12

who used the cathode ray tube to discover electrons’ charge

Answer 12

JJ Thomson

Question 13

The _______ is the densest part of the atom, _____ charged, and contains most of the ___ of the atom

Answer 13

nucleus, positively, mass

Question 14

atoms of the same element that have a different mass number

Answer 14

isotope

Question 15

mass number= ___+____

Answer 15

protons+, neutrons0

Question 16

an isotope has __________ atomic mass

Answer 16

whole number

Question 17

the energy of an electron is determined by _____-distance from the nucleus

Answer 17

energy levels

Question 18

what is a quantum

Answer 18

fixed amount of energy (each electron is described by 4 quantum numbers)

Question 19

80% as a decimal is ___ with ____ sig figs

Answer 19

.8, 1

Question 20

molar mass is measured in___

molecular mass is measure in ____

Answer 20

grams, amus

Question 21

how would you find the molar mass of H2SO4

Answer 21

2(1.0)+32.1+64.0=98.1g

find the elements’ masses and add up

Question 22

how do you find percent abundance of an element in a compound

Answer 22

put the molar mass of the element over the total molar mass of the compound. divide and multiply by 100

Question 23

how many protons are in 12C

electrons?, neutrons?

Answer 23

6,6,6

Question 24

the number of ____ in an element will never change

Answer 24

protons

Question 25

all carbon atoms have __ protons

Answer 25

6

Question 26

what do all hydrogen atoms (and ions) have in common

Answer 26

1 electron

Question 27

what is the significance of the atomic number Z above each element in the periodic table

Answer 27

it's the number of protons in the nucleus of that element

Question 28

what feature distinguishes a neutral atoms from an ion

Answer 28

an ion is charged and has an unequal amount of protons and electrons. Atoms are neutral and have an equal amount of protons and neutrons

Question 29

why is most of the mass of an atom within the nucleus

Answer 29

it has protons and neutrons while the outside only has electrons and free space

Question 30

in large atoms the number of protons is ____ than the number of neutrons

Answer 30

less

Question 31

uranium has 92 protons and 145 neutrons. write its symbol

Answer 31

237 U 92

Question 32

A X Z what does each represent

Answer 32

a-mass number x-nuclide z-atomic number

Question 33

all elements have _______ isotopes

Answer 33

at least one

Question 34

% composition=

Answer 34

massX/total mass x 100%

Question 35

what error margin is acceptable | when adding percent compositions, what values besides 100% are acceptable?

Answer 35

10% error | 99.9%, 100.1%

Question 36

the mass of a mole=formula mass expressed in ___

Answer 36

grams

Question 37

there are 22.4 L/

Answer 37

mole

Question 38

there are _______ particles per mol | what particles are acceptable here and what is this number called

Answer 38

6.022 x 10^23 | atoms, molecules, formula units, Avogadro's number

Question 39

every mole of something equals its formula mass of___

Answer 39

grams

Question 40

.8%==

Answer 40

.008

Question 41

Isotopes have ________ mass numbers (or, number of neutrons) but the __________ atomic number (number of protons)

Answer 41

Different, same

Question 42

What is Cu?

Answer 42

Copper-64

Question 43

How would you figure out how many H Atoms are in C12H22O11

Answer 43

Find out how many molecules total this is and multiply by 22

Question 44

``` 127.5 What place is the 2 in? 1? 7? 5? (Make sure you remember this in your answer with sig figs ```

Answer 44

Tens, hundreds, ones, tenths

Question 45

The __________ of an element is the weighted average of the masses of the isotopes of that element

Answer 45

average atomic mass