What determines an element’s position in the Periodic Table?
Proton number
The number of protons defines the element and its position.
How are elements classified into blocks in the Periodic Table?
By highest energy sub-shell
The block corresponds to the type of sub-shell being filled by the outer electrons.
Fill in the blank:
Elements in the _______ block have their outer electrons entering an s sub-shell.
s
Groups 1 and 2 are typical examples of s-block elements.
True or False:
The p block occupies the right-hand side of the Periodic Table.
True
It includes Groups 13–18 where electrons fill p orbitals.
Which block contains the transition metals?
d block
These elements have electrons filling the d sub-shell.
True or False:
The f block contains the lanthanides and actinides.
True
These elements involve filling of the f sub-shell.
Fill in the blank:
The block of an element depends on which type of ___-____ is being filled by electrons.
sub-shell
Sub-shells include s, p, d and f orbitals.
What block do Group 1 elements belong to?
s block
Their outer electron occupies an s orbital.
True or False:
Elements in the same block must have the same number of electrons.
False
They share the same type of sub-shell being filled, not the same number of electrons.
What type of sub-shell is being filled in p-block elements?
p sub-shell
These sub-shells contain three orbitals.
What general trend is observed in atomic radius across Period 3 from Na to Ar?
Decreases
Increasing nuclear charge pulls electrons closer while shielding remains similar.
What happens to first ionisation energy across Period 3 from Na to Ar?
Increases
Stronger nuclear attraction makes electrons harder to remove.
Fill in the blank:
Across Period 3, atomic radius decreases because nuclear _______ increases.
charge
More protons attract the same outer shell of electrons more strongly.
True or False:
Shielding increases significantly across Period 3.
False
Electrons are added to the same shell, so shielding changes little.
Why does atomic radius decrease across Period 3?
Greater nuclear attraction
More protons pull the electron cloud closer to the nucleus.
True or False:
The first ionisation energy is the energy required to remove one electron from each atom in one mole of gaseous atoms.
True
This definition applies to the first ionisation energy.
Fill in the blank:
A higher nuclear charge leads to a _______ first ionisation energy.
higher
Electrons are held more strongly by the nucleus.
What type of structure explains the high melting points of sodium, magnesium and aluminium?
Metallic lattice
Strong metallic bonding requires significant energy to break.
True or False:
Silicon has a very high melting point because it forms a giant covalent structure.
True
Strong covalent bonds extend throughout the lattice.
Why do melting points drop sharply from silicon to phosphorus?
Molecular structure
Silicon is macromolecular whereas P4 molecules are held together by weak intermolecular forces.
Fill in the blank:
Phosphorus, sulfur and chlorine have relatively low melting points due to _______ intermolecular forces.
weak
These substances consist of simple molecular structures.
Why does sulfur have a higher melting point than phosphorus?
Larger molecules
S8 molecules experience stronger London forces than P4 molecules.
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Physical Chemistry: Atomic Structure50
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Physical Chemistry: Amount of Substance47
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Physical Chemistry: Bonding and Structure90
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Physical Chemistry: Energetics62
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Physical Chemistry: Kinetics55
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Physical Chemistry: Equilibria (Qualitative)24
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Physical Chemistry: Equilibria (Quantitative)12
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Physical Chemistry: Acids, Bases and Buffers69
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Physical Chemistry: Thermodynamics27
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Physical Chemistry: Redox and Electrochemistry63
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Inorganic Chemistry: Periodicity22
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Inorganic Chemistry: Group 2 and Halogens55
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Inorganic Chemistry: Period 3 and Oxides35
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Inorganic Chemistry: Transition Metals134
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Inorganic Chemistry: Qualitative Analysis20
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Organic Chemistry: Basic Concepts42
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Organic Chemistry: Hydrocarbons85
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Organic Chemistry: Halogenoalkanes and Alcohols79
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Organic Chemistry: Carbonyl Compounds20
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Organic Chemistry: Carboxylic Acids and Derivatives25
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Organic Chemistry: Aromatic Compounds29
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Organic Chemistry: Amines and Biological Molecules102
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Organic Chemistry: Polymers24
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Organic Chemistry: Organic Synthesis12
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Analytical Chemistry: Spectroscopy and Chromatography62
