Periodic Table and Bonding

How are elements arranged in the Periodic Table?

In order of increasing atomic number, in periods (rows) and groups (columns).

What are groups and periods in the Periodic Table?

Groups = vertical columns (same number of outer electrons, similar properties). Periods = horizontal rows (same number of electron shells).

How can you deduce the electronic configuration of an element from its position in the Periodic Table?

Period number = number of shells. Group number = number of outer electrons (main groups).

What is the electronic configuration for calcium (atomic number 20)?

2.8.8.2

How can you classify an element as a metal or non-metal using electrical conductivity and the nature of oxides?

Metals conduct electricity and form basic oxides. Non-metals do not conduct (except graphite) and form acidic oxides.

Where are metals and non-metals found in the Periodic Table?

Metals are left of the stepped line, non-metals are right of it, and metalloids are along the stepped line.

How is the electronic configuration of a main group element related to its group number and period number?

Group number = number of outer shell electrons. Period number = number of occupied shells.

Why do elements in the same group have similar chemical properties?

They have the same number of outer shell electrons, leading to similar bonding and reactivity.

Why are noble gases (Group 0) unreactive?

They have full outer shells (stable octet/duet), resulting in no tendency to gain, lose, or share electrons.

How are positive and negative ions formed?

Metals lose electrons to form positive ions, while non-metals gain electrons to form negative ions.

What are the ion charges for Group 1, Group 2, Group 7, Aluminium, Sulphate and Ammonium

Group 1 +1, Group 2 +2, Group 7 -1, Al³⁺ +3, SO₄²⁻ -2, NH₄⁺

What are the chemical formulae for Sodium Oxide, Magnesium Chloride, Aluminium Oxide, Calcium Hydroxide, Ammonium Sulphate, Iron Nitrate

a) Na₂O b) MgCl₂ c) Al₂O₃ d) Ca(OH)₂ e) (NH₄)₂SO₄ f) Fe(NO₃)₃.

What holds the ions together in an ionic compound?

Strong electrostatic attraction between oppositely charged ions.

Why do ionic compounds have high melting and boiling points?

They have a giant ionic lattice with many strong electrostatic forces, requiring a large amount of energy to break apart.

Why do solid ionic compounds not conduct electricity, but molten ionic compounds and aqueous solutions do?

In solid form, ions are fixed in a lattice and cannot move; in molten or aqueous forms, ions are free to move and carry charge.

What is a covalent bond?

A pair of electrons shared between two atoms (usually non-metals).

How does electrostatic attraction explain covalent bonding?

Shared electrons are attracted to both nuclei, holding the atoms together.

Why are simple molecular substances usually gases, liquids, or low-melting solids?

They have weak intermolecular forces, requiring little energy to separate.

Why do the melting and boiling points of simple molecular substances generally increase with increasing relative molecular mass?

Larger molecules have more electrons, leading to stronger van der Waals forces and requiring more energy to separate.

Why do substances with giant covalent structures have very high melting and boiling points?

They have strong covalent bonds throughout the giant lattice, requiring huge energy to break.

Compare the structures and properties of diamond, graphite, and fullerene (C₆₀).

Diamond: tetrahedral, very hard, insulator, high mp. Graphite: layered hexagons, soft/lubricant, conducts, high mp. C₆₀: spherical molecules, low mp (compared), insulator, soluble.

Why do most covalent compounds not conduct electricity?

They lack free ions or delocalised electrons (except graphite).

What is metallic bonding?

The strong electrostatic attraction between positively charged metal ions and a shared ‘sea of delocalised electrons’

Why are metals good conductors of electricity and heat?

Delocalised electrons are free to move, carrying electric charge and kinetic energy (heat).

Why are metals malleable and ductile?

Layers of ions can slide over each other when hammered or drawn, while delocalised electrons hold the structure together.