Atomic Structure & Periodic Table

Question 1

What was stated in Dalton’s
atomic theory? (4)

Answer 1

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 2

What did Thompson discover
about electrons? (3)

Answer 2

They have a negative charge
● They can be deflected by electromagnetic
fields
● They have very small mass

Question 3

Explain the current model of
the atom.

Answer 3

Protons and neutrons are found in the nucleus
● Electrons orbit the nucleus in shells
● The 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 4

What is the charge of a proton
and an electron?

Answer 4

What is the charge of a proton and an electron?
Proton = +1
Electron = -1

Question 5

Which particle has the same
mass as proton?

Answer 5

Neutron

Question 6

Which two particles make up
most of an atom’s mass?

Answer 6

Protons and neutrons

Question 7

What does the atomic number
show about an element?

Answer 7

Number of Protons

Question 8

How do you calculate mass number

Answer 8

Protons + Neutrons

Question 9

What is a isotope

Answer 9

Atoms of the same element with different number of neutrons and
(therefore different mass number)

Question 10

Why do different isotopes of
the same element react in the
same way

Answer 10

Neutrons have no impact on the chemical reactivity
● Reactions involve electrons, isotopes have
the same number of electrons in the same
arrangement

Question 11

Define relative atomic mass

Answer 11

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

Question 12

Define relative isotopic mass

Answer 12

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

Question 13

The relative isotopic mass is
same as which number?

Answer 13

Mass number

Question 14

What two assumptions are made when calculating mass number?

Answer 14

Contribution of the electron is neglected

Mass of both proton and neutron is taken as 1.0u

Question 15

How to calculate the relative molecular mass and relative
formula mass

Answer 15

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

Question 16

What are the uses of mass spectrometry?

Answer 16

Identify unknown compounds
● Find relative abundance of each isotope of an element
● Determine structural information

Question 17

What does the principal quantum number indicate

Answer 17

The shell occupied by the electrons

Question 18

What is a shell

Answer 18

A group of orbitals with the same principal quantum number

Question 19

How many electrons can the 1st shell hold

Answer 19

2

Question 20

How many electrons can the 2nd shell hold

Answer 20

8

Question 21

How many electrons can the 3rd shell hold

Answer 21

18

Question 22

How many electrons can the 4th shell hold

Answer 22

32

Question 23

What is an orbital

Answer 23

A region around the nucleus that can hold up to two electrons with opposite spins

Question 24

How many electrons can an orbital hold

Answer 24

2

Question 25

What are the 4 types of orbitals?

Answer 25

s p d f

Question 26

What is the shape of a S-orbital?

Answer 26

Spherical

Question 27

What is the shape of a p-orbital

Answer 27

Dumb-bell shape

Question 28

How many orbitals are found in a S subshell

Answer 28

1

Question 29

How many electrons can beheld in a S subshell

Answer 29

2

Question 30

How many orbitals does P subshell have

Answer 30

3

Question 31

How many electrons can be held in a P subshell

Answer 31

6

Question 32

How many orbitals are present in a D subshell

Answer 32

5

Question 33

How many electrons can be held in a D subshell

Answer 33

10

Question 34

How many orbitals are found in a F subshell

Answer 34

7

Question 35

How many electrons can fill F subshell

Answer 35

14

Question 36

When using ‘electrons in box’ representation, what shape is used to represent the electrons

Answer 36

arrows

Question 37

What letter used to represent shell number

Answer 37

n

Question 38

From which shell onwards is S orbital present

Answer 38

n=1

Question 39

From which shell onwards is P orbital present

Answer 39

n=2

Question 40

From which shell onwards is D orbital present

Answer 40

n=3

Question 41

From which shell onwards is F orbital present

Answer 41

n=4

Question 42

What are the rules by which electrons are arragned in the shell?

Answer 42

Electrons are added one at a time Lowest available energy level is filled first Each energy level must be filled before the next one can fill Each orbital is filled singly before pairing 4s is filled before 3d

Question 43

Why does 4s orbital fill before 3d orbital

Answer 43

4s orbital has a lower energy than 3d before its filled

Question 44

Abbreviated notation?

Answer 44

Noble Gas before the element

Question 45

How are the group number and electrons related

Answer 45

Group no. = no. electrons outer shell

Question 46

WHat is a period

Answer 46

Rows

Question 47

What is a group

Answer 47

Columns

Question 48

How are the elements arranged

Answer 48

Arranged in the order of increasing atomic numbers

Question 49

Does the group number indicate horizontal or vertical columns in the periodic table

Answer 49

Vertical Column

Question 50

What is meant by periodicity

Answer 50

The repeating trends in chemical and physical properties

Question 51

What change happens across each period

Answer 51

Elements change from metals to non-metals

Question 52

Define first ionisation energy

Answer 52

Enthalpy required for X(g) -> X+(g) + e-

Question 53

What are the factors that affect ionisation energy

Answer 53

● Atomic radius ● Nuclear charge ● Electron shielding or screening

Question 54

What is the trend of first IE across P3

Answer 54

Increases because: Increased nuclear charge, Decreased atomic radius, Same electron shielding Dips at Al: outer electron is in 3p -> higher energy; less energy to remove Dips at S: because 3p orbital contains two electrons: repulsions between paired electrons -> less energy required to lose

Question 55

Why does first IE decrease between G2 G3

Answer 55

Decreases between 2 to 3 because in group 3 the outermost electrons are in p orbitals. Whereas in group 2 they are in s orbital, so the electrons are easier to be removed

Question 56

Why does first ionisation energy decrease between group 5 to 6

Answer 56

The decrease between 5 to 6 is due to the group 5 electrons in p orbital which are single electrons. ● In group 6 the outermost electrons are spin paired, with some repulsion. ● Therefore the electrons are slightly easier to remove.

Question 57

Does first ionisation increaseor decrease between the end of one period and the start of next? Why?

Answer 57

Decrease ● There is increase in atomic radius ● Increase in electron shielding

Question 58

Does first ionisation increase or decrease down a group? Why

Answer 58

Decrease ● Shielding increases → weaker attraction ● Atomic radius increases → distance between the outer electrons and nucleus increases → weaker attraction ● Increase in number of protons is outweighed by increase in distance and shielding

Question 59

Describe the structure, forces and bonding in every element across period 2

Answer 59

Li & Be → giant metallic ; strong attraction between positive ions and delocalised electrons ; metallic bonding ● B & C → giant covalent ; strong forces between atoms ; covalent ● N 2 ,O 2 ,F 2 ,Ne → simple molecular ; weak intermolecular forces between molecules ; covalent bonding within molecules and intermolecular forces between molecules

Question 60

Describe the structure, forces and bonding in every element across period 3

Answer 60

Na, Mg, Al : giant metallic Si -> giant covalent P4, S8, Cl2, Ar: simple molecular