Topic 1 Atomic Structure & Periodic Table

Question 1

What is the maximum number of electrons in each shell?

Answer 1

Shell 1 - 2
Shell 2 - 8
Shell 3 - 18
Shell 4 - 32
Shell 5 - 50

Question 2

How many sub shells are in each shell?

Answer 2

Shell 1 - 1
Shell 2 - 2
Shell 3 - 3
Shell 4 - 4

Question 3

What are the 4 different types of sub shells?

Answer 3

S, P, D and F orbitals

Question 4

What are the sub shells in each shell?

Answer 4

Shell 1 - 1s
Shell 2 - 2s, 2p
Shell 3 - 3s, 3p, 3d
Shell 4 - 4s, 4p, 4d, 4f

Question 5

What are the electron configurations of H, O, Na, Cl and Ca?

Answer 5

H - 1s(1)
O - 1s(2) 2s(2) 2p(4)
Na - 1s(2) 2s(2) 2p(6) 3s(1)
Cl - 1s(2) 2s(2) 2p(6) 3s(2) 3p(5)
Ca - 1s(2) 2s(2) 2p(6) 3s(2) 3p(6) 4s(2)

Question 6

What is the order of sub shells in the electron configuration?

Answer 6

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s …

Question 7

What is the Aufbau principle?

Answer 7

Electrons fill orbitals from the lowest energy first. This means the sub shells fill in this order: s, p, d, f.

Question 8

What is Hund’s rule?

Answer 8

Electrons will fill all orbitals with the same (up) spin first before filling the opposite (down) spin.

Question 9

How can you shorten electron configurations?

Answer 9

Put the noble gas before the element in square brackets then continue the electron configuration from there.

Cl:
Was - 1s(2) 2s(2) 2p(6) 3s(2) 3p(5)
Now - [Ne] 3s(2) 3p(5)

Ca:
Was - 1s(2) 2s(2) 2p(6) 3s(2) 3p(6) 4s(2)
Now - [Ar] 4s(2)

Question 10

How many orbitals are in each sub shell?

Answer 10

s - 1
p - 3
d - 5
f - 7

Question 11

What happens to the electron configuration when positive and negative ions are added?

Answer 11

Positive - Electrons are taken away from the highest energy level

Negative - Electrons are added to the highest energy level.

Question 12

When are electrons not removed/added to the highest energy level for an ion’s electron configuration?

Answer 12

When the element is in the transition metals. For example in elements in the first row of transition metals

Ti: [Ar] 4s(2) 3d(2)
Ti+: [Ar] 4s(1) 3d(2)
Ti2+: [Ar] 3d(2)

Question 13

What is the definition for relative atomic mass?

Answer 13

The average mass of 1 atom relative to 1/12th the mass of a 12C atom. (The Ar)

Question 14

What is the definition of relative isotopic mass?

Answer 14

The mass of an atom of the isotope relative to 1/12th the mass of a 12C atom.

Question 15

What is the definition of relative molecular mass?

Answer 15

The relative molecular mass of an element or compound is the sum of the relative atomic masses of all the atoms in its molecular formula. (The Mr)
E.g. O2 = 2 x (Ar of O) = 2 x 16 = 32

Question 16

What is the atomic number of an element?

Answer 16

The number of protons in the nucleus of an atom of the element.

Question 17

What is an isotope of an element?

Answer 17

Atoms of an element with the same proton number (atomic number) but that differ with neutron number in the nucleus.

Question 18

What is the mass number of an element?

Answer 18

The number of protons and neutrons in the nucleus of an atom of the element.

Question 19

What are the relative masses of protons, neutrons and electrons?

Answer 19

Proton - 1
Neutron - 1
Electron - 1/1840

Question 20

What are the relative charges of protons, neutrons and electrons?

Answer 20

Proton - +1
Neutron - 0
Electron - -1

Question 21

What is the definition for relative formula mass?

Answer 21

The relative formula mass of a compound is the sum of the relative atomic masses of all the atoms in it’s formula. (The Mr)
E.g. Mg(NO3)2 = 24.3 + 2(14 + (16x3)) = 148.3

Question 22

Why is relative formula mass used instead of relative molecular mass for metal compounds?

Answer 22

Relative formula mass is used because metal compounds consist of giant structures of ions and not molecules and this avoids the suggestion that their formulae are molecules.

Question 23

What is an Orbital?

Answer 23

A region within an atom that can hold up to 2 electrons with opposite spins.

Question 24

What are the shapes of S and P orbitals?

Answer 24

S - Sphere (Gets bigger for every shell e.g. 1s orbital is inside 2s orbital)

P - Dumbbell shaped (All 3 p orbitals are on each axis - x, y, and z.)

Question 25

How do electrons fill orbitals?

Answer 25

Electrons fill orbitals singly (with up spins first) until all orbitals in the sub shell have one electron. At this point they fill the rest (with down spins).

Question 26

How do you calculate relative atomic mass?

Answer 26

Total mass of all isotopes / Total number of isotopes

e.g. Chlorine - Cl 35 and Cl 37
Relative Proportion: 3-1
(3 x 35) + (1 x 37) / 3 + 1 = 35.5

Question 27

What does VIADD stand for?

Answer 27

Vaporisation, Ionisation, Acceleration, Deflection, Detection

Question 28

When do you use VIADD?

Answer 28

To name the processes used in a mass spectrometer.

Question 29

What is the definition of first ionisation energy?

Answer 29

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive ions.

Question 30

What is the trend in first ionisation energy down a group?

Answer 30

The ionisation energy decreases because:

• The filled inner shells provide a shielding affect which lowers the effective nuclear pull.
• The size of the atom becomes greater, therefore the electron is further away from the nucleus which results in a lower nuclear attraction.

As a result of this, less energy is needed to overcome the force of attraction from the nucleus.

Question 31

What is the trend in first ionisation energy across a period?

Answer 31

The ionisation energy increases because:

• The atom has a greater atomic number than the previous atom which results in a greater nuclear pull.

As a result of this more energy is needed to overcome this force.

Question 32

What is the definition for successive ionisation energy?

Answer 32

The energy required to remove one mole of electrons from one mole of gaseous unipositive ions to form one mole of gaseous dipositive ions.

Question 33

How does the sub-shell that the electron is removed from affect the ionisation energy?

Answer 33

An electron in the highest energy level is more easily removed so has a lower ionisation energy.

An electron in an intermediate energy level is harder to remove than that of one in the highest but easier than that of one in the lowest energy level so has intermediate ionisation energy.

An electron in the lowest energy level is much harder to remove so has the highest ionisation energy.

Question 34

What is shielding?

Answer 34

The effect of the inner electrons which reduces the pull of the nucleus on the electrons in the outer shell of an atom. Because of shielding, electrons in the outer shells are attracted by an ‘effective nuclear charge’ which is less than the full charge on the nucleus.

Question 35

What are mass spectrometers used for?

Answer 35

They are used to determine the relative atomic mass of an element or compound.

Question 36

How do mass spectrometers work?

Answer 36

Gaseous samples of elements or compounds are bombarded with high-energy electrons causing ionisation and resulting in positive ions being produced. The ions are accelerated by an electric field and bent into a circular path by a magnetic field. The radius of the path that different ions take depends on their mass. The ions are then detected and the number of ions at a particular mass can be determined.