structure of the atom

Question 1

what can a simple model of atomic structure explain

Answer 1

many chemical and nuclear processes

Question 2

how many subatomic particles do atoms have

Answer 2

3

Question 3

what are the three subatomic particles

Answer 3

proton
neutron
electron

Question 4

what subatomic particles form the nucleus

Answer 4

protons and neutrons

Question 5

what do the electrons do

Answer 5

orbit the nucleus in shells

Question 6

what is the radius of most atoms

Answer 6

0.1nm

Question 7

what is the radius of the nucleus

Answer 7

1x10^-15m

Question 8

what is the mass of a proton

Answer 8

1

Question 9

what is the mass of a neutron

Answer 9

1

Question 10

what is the mass of an electron

Answer 10

0.00055

Question 11

what is the charge of a proton

Answer 11

+1

Question 12

what is the charge of a neutron

Answer 12

0

Question 13

what is the charge of an electron

Answer 13

-1

Question 14

what does the nucleus account for

Answer 14

most of the mass of an atom

Question 15

why is an atom neutral overall

Answer 15

the number of protons = the number of electrons. the opposite and equal charges cancel each other out

Question 16

which subatomic particle interacts in chemical reactions

Answer 16

electrons

Question 17

how can we describe the nucleus

Answer 17

using the atomic number (Z) and mass number (A)

Question 18

what is the atomic number

Answer 18

the number of protons in the nucleus. it is numerically equal to the charge on the nucleus

Question 19

is the atomic number the same for every atom of an element

Answer 19

yes

Question 20

what is the mass number

Answer 20

the number of protons plus the number of neutrons in the nucleus

Question 21

what do nuclear symbols identify

Answer 21

the mass number and the atomic number as well as the symbol for the element

Question 22

what is the nuclear symbol for iodine

Answer 22

131
I
53

Question 23

what does the top number represent

Answer 23

the mass number

Question 24

what does the bottom number represent

Answer 24

atomic number

Question 25

why is the atomic number sometimes omitted in nuclear symbols

Answer 25

the chemical symbol tells us which element it is anyways

Question 26

what is an isotope

Answer 26

atoms of the same element with the same number of protons but different number of neutrons

Question 27

isotopes have the same atomic number but...

Answer 27

...different mass number

Question 28

what do most elements naturally exist of

Answer 28

isotopes

Question 29

what is the relative atomic mass of an element

Answer 29

an average of the masses taking into account their abundance

Question 30

how is it possible for chlorine to have 18.5 neutrons

Answer 30

atoms of the same element are not all identical, they can have a different mass. the number of neutrons in the nucleus can vary - the mass number is therefore a weighted average

Question 31

do the number of protons and electrons change in isotopes

Answer 31

no

Question 32

how are isotopes written

Answer 32

by the symbol followed by the mass number

Question 33

the higher the number of neutrons...

Answer 33

...the greater the mass

Question 34

what does a higher number of neutrons tend to do

Answer 34

change physical properties slightly

Question 35

define relative isotopic mass

Answer 35

mass of isotope of atom compared with one twelfth of the mass of an atom of carbon-12

Question 36

define relative atomic mass

Answer 36

weighted mean mass of one atom of an element compared with one twelfth the mass of an atom of carbon-12

Question 37

how do you work out relative atomic mass

Answer 37

(mass x abundance) + (mass x abundance) / 100

Question 38

what is empirical formula

Answer 38

shows simplest whole number ratio of each type of atom

Question 39

steps to work out empirical formula

Answer 39

- write each symbol - write each mass in g - write each Ar - find the number of moles - divide by the smallest number of moles - check for whole numbers - write the formula

Question 40

work out the empirical formula of an element containing 0.72g of Mg and 0.48g of O

Answer 40

Mg - 0.72/24 = 0.03 mol O - 0.48/16 = 0.03 0.03/0.03 = 1 0.03/0.03 = 1 1:1 ratio MgO