Chemical Bonding I Flashcards
Chemical bonds
Electrostatic attractive forces between particles resulting in a lower energy arrangement
Particles
Atoms, ions, or molecules
Formation of chemical bond involves
Redistribution of electrons in the valence (outermost) shells of the atoms concerned
Giant ionic structure
Ionic bond
Giant metallic structure
Metallic bond
Giant covalent structure
Covalent bond
Simple covalent structure
Consists of covalent bond & intermolecular forces of attraction
Hydrogen bonding exists…
Between water molecules
Ionic bonds
Electrostatic forces of attraction (FOA) between oppositely charged ions
Kernel
Nucleus + inner shell electrons
Nature of ionic bonds
Non-directional -> each ion attracts ions of opposite charge in all directions
Are strong bonds
Covalent bond
Electrostatic FOA between positively charged nuclei of each atom & their shared pair of electrons (negatively charged)
Bond pair of electrons
Valence electrons involved in the formation of the covalent bond
Lone pair of electrons
Valence electrons not involved in bonding
“Normal” CB
Both orbitals are singly occupied with an electron of opposite spin to each other
Dative CB
1 orbital filled with a pair of electrons while the other orbital is an empty orbital
Localised
Bonding electron pair is confined within the valence orbitals of the two atoms
Nature of covalent bonds
Strong (each pair of shared electrons is attracted by both the positively charged nuclei involved in the bonding)
Directional
Bond length
Inter-nuclear distance between two atoms involved in the bonding
The optimum bonding distance between ^
Maximum overlap of atomic orbitals containing shared electron pair
Forms molecular orbital
Sigma bond
Formed by head-on (or end-on) overlap
Pi bond
Formed when there’s sideways overlap of atomic orbital of p orbitals only
Bond energy
Energy, in kJ mol−1, required to break 1 mole of covalent bonds between 2 atoms in the gaseous state, or a particular type of bond in a gaseous poly atomic molecule to give gaseous atoms
Uses of bond energy
Compare strengths & reactivities
Estimate enthalte (heat) changes
Bond order
Number of covalent bonds formed between 2 atoms involved in the bonding
Electronegativity for CB A-B
Measure of the ability of atoms A or B to attract the bonding electrons
Factors contributing to high degree of covalency in ionic compounds
High cation charge
Small size of cation
Large size of anion
Bond angles
180
120
109
90 & 120
90
Factors affecting bond angles
Number of lone pairs of electrons
Electronegativity of central atom
Size of atoms attached
