1.2 Bonding 🪢

Bonding

way in which molecules and structures are held together

Molecule

particle consisting of two or more atoms chemically bonded together

Compound

substance consisting of two or more elements chemically combined

Dot and cross diagram

shows arrangement of atoms or ions, same elements have same electrons (✕ / ⬤)

Covalent bond

formed by shared pair of electrons between non-metals, neutral charge

Lone pair electrons

Electrons paired up but not part of covalent bond

Stick diagram/ structure

single line for covalent bond, double line for double covalent etc

Strength of covalent bonds

Very strong and takes large amount of energy to break

Common covalent substances

H₂, Cl_2, HCl H₂O, NH₃, CH₄

Diatomic

two atoms covalently bonded in a molecule

Diatomic elements

H₂, N₂, O₂ + Group 7

Double covalent bond

bond which atoms share two pairs of electrons e.g carbon dioxide or oxygen

Triple covalent bond

bond which atoms share three pairs of electrons e.g nitrogen

Metallic bonding

attraction between delocalised electrons and positive ions in regular lattice

Metals typically form

positive ions (cations) by delocalising outer electrons

Ionic bonding

electrostatic attraction between oppositely charged ions, metal and non-metals

Electrons in ionic bonding

transferred from metal atom to non-metal atom

Examples of Ionic compounds

NaCl, MgO

Drawing ionic bonds

1. draw electronic configuration of each atom

2. work out how many electrons are transferred

3. draw configuration of ions formed

4. write the charge of each ion [ ]^±

Ionic formula

simplest whole number ratio of the ions in giant ionic lattice

Ion

charged particle formed when an atom gains or loses electrons

Anion

negatively charged ion, ends in -ide

Cation

positively charged ion

Molecular ion (back of data leaflet)

charged particle containing more than one atom e.g OH^-