Covalent Bonding ● Covalent bond – Bonds between two nonmetals. Electrons are shared, rather than transferred. ● Electronegativities are not strong enough to pull electrons away completely, therefore, a covalent bond is formed from sharing electrons Molecules – chemical compounds made from covalent bonds Molecules tend to be soft or brittle Low melting points Poor conductors of heat & electricity Example: Chlorine atoms bonding to form Cl 2 Cl + Cl → Cl 2 Lewis-Dot diagrams for covalent bonds are different than ionic bonds A dash is used to represent a pair of “shared” electrons
Types of Covalent Bonding Single Covalent Bond – One pair of electrons are shared between two nonmetals. – Ex: Hydrogen bonding with Hydrogen Double Covalent Bond – Two pairs of electrons are shared between two nonmetals. – Ex: Oxygen bonding with Oxygen
Types of Covalent Bonding Triple Covalent Bond – three pairs of electrons are shared between two nonmetals. – Ex: Nitrogen bonding with Nitrogen
Quick Tips For Bonding Group 17 Halogens and Hydrogen only form one covalent bond - one pair of electrons is shared to make a complete octet Group 15 Nonmetals form three covalent bonds - one triple bond, or a combination of double and single bonds. Carbon can form up to four covalent bonds. - any combination of single, double, or triple bonds Group 16 Nonmetals form two covalent bonds A double bond with another non-metal 2 single covalent bonds
Bond Polarity Nonpolar Covalent Bond – The bond created from an equal sharing of electrons. Atoms of the same element have the same electronegativity and produce nonpolar bonds Ex. Br 2, I 2, N 2, Cl 2, H 2, O 2, F 2 Look familiar? Polar Covalent Bond – Electrons are not shared equally. - Between two different nonmetals, one will have a higher electronegativity - the higher electronegativity produces a partial negative charge - the lower electronegativity has a partial positive charge - δ -- and δ + are used to show a partial negative and partial positive charge Electronegativity Hydrogen: 2.2 Fluorine: 4.0