Atomic Structure and Isotopes

Question 1

What are isotopes?

Answer 1

Isotopes are atoms of the same element with different numbers of neutrons and different masses

Question 2

What was stated in Dalton’s

atomic theory? (4)

Answer 2

Atoms are tiny particles made of elements

Atoms cannot be divided
All the atoms in a element are the same
Atoms of one element are different to those of
other elements

Question 3

What did Thompson discover

about electrons? (3)

Answer 3

They have a negative charge

● They can be deflected by magnet and
electric field
● They have very small mass

Question 4

Explain the plum pudding

model

Answer 4

Atoms are made up of negative electrons
moving around in a sea of positive
charge

Question 5

What were Rutherford’s
proposal after the gold leaf
experiment? (4)

Answer 5

Most of the mass and positive charge of the atom are in the nucleus

Electrons orbit the nucleus

Most of atom’s volume is the space between the
nucleus and the electrons

Overall positive and negative charges must balance

Question 6

Explain the current model of

the atom

Answer 6

Protons and neutrons are found in the nucleus
● Electrons orbit in shells
● Nucleus is tiny compared to the total volume of atom
● Most of atom’s mass is in the nucleus
● Most of the atom is empty space between the nucleus
and the electrons

Question 7

Which two particles make up

most of atom’s mass?

Answer 7

Protons and neutrons

Question 8

Which letter is used to
represent the atomic number
of an atom?

Answer 8

Z

Question 9

What does the atomic number

tell about an element?

Answer 9

The number of protons in the atom

Question 10

Which letter represents the

mass number?

Answer 10

A

Question 11

Why does different isotopes of
the same element react in the
same way? (2)

Answer 11

Same electron configuration

Neutrons have no impact on the chemical reactivit

Reactions involve electrons, isotopes have
the same number of electrons in the same
arrangement

Question 12

What are ions?

Answer 12

Charged particles that are formed when an

atom loses or gains electrons

Question 13

What is the unit used to
measure atomic masses
called?

Answer 13

u

Question 14

The relative isotopic mass is

same as which number?

Answer 14

Mass number

Question 15

What two assumptions are
made when calculating mass
number?

Answer 15

Contribution of the electron is neglected

Mass of both proton and neutron is taken
as 1.0 u

Question 16

How to calculate the relative
molecular mass and relative
formula mass?

Answer 16

Both can be calculated by adding the
relative atomic masses of each of the
atom making up the molecule or the
formula

Question 17

Which are the 4 elements that
don’t tend to form ions and
why?

Answer 17

The elements are beryllium, boron, carbon
and silicon
Requires a lot of energy to transfer outer shell
electrons

Question 18

What are molecular ions?

Answer 18

Covalently bonded atoms that lose or gain electrons

Question 19

What is the charge of an

ammonium ion?

Answer 19

+1 → NH4

Question 20

What is the charge of a nitrate

ion?

Answer 20

-1 → NO3-

Question 21

What is an empirical formula?

Answer 21

Simplest whole number ratio of atoms of

each element present in a compound

Question 22

How to calculate empirical

formula?

Answer 22

Divide the amount of each element by its molar
mass

Divide the answers by the smallest value obtained

If there is a decimal, divide by a suitable number
to make it into a whole number Divide the amount of each element by its molar
mass

Question 23

For which substance do you use the term relative molecular mass?

Answer 23

Simple molecules

Question 24

For which substance do you use the term relative formula mass?

Answer 24

Compounds with giant structures