bonding

BondingBy Mary Agarwala

Chemical Bonds? What are they? Why do atoms form them? Why are some stronger than

others?

Ionic Bonding + charged ion is attracted to a – charged

ion A nonmetal + a metal = ionic bond Ionic compound is entirely made up of ions Positively charged ion (Cation) Negatively charged ion (Anion) Ex. NaCl

Ionic properties High melting points which

means it ionic bonds are strong bond

Brittle Dissolves in water, a process

that breaks the ionic bonds and separates the ions (makes solutions that conduct electricity)

Polar…”Likes dissolves likes” Liquid (motlen) ionic

compounds conduct electricity

Solid ionic compounds do not conduct electricity well

OCTET RULEAtoms tend to gain,

lose, or share electrons in order to acquire a full set of valence electrons

Lewis Dot Diagrams

Valence electrons are represented as dots placed around the element symbol

KNOW HOW TO WRITE IONIC COMPOUNDS

Empirical formula vs. Molecular formula

Empirical Formula

Denote the ratio of ions in a compound

Chemical formula

The lowest possible whole number subscripts for the elements

The compound wants to be electrically neutral

Molecular Formula

Molecular compound

Describes the composition of a molecular compound

Tells how many atoms are in a single molecule of the compound

Ex. Glucose (C6H12O6)

Covalent Bonds

-A covalent bond is formed by a shared pair of electrons

between two atoms-Each atom wants to be

“octet happy”-Nonmetal + nonmetal =

Covalent bond-This is best shown by

combining atoms’ Lewis structures

Multiple BondsDouble Bonds

(show picture)

(text book pg 239. Eq.4)

Triple Bonds (show picture)

(text book pg. 239 Eq.5)

Exceptions to the Octet Rule

Atoms with less than an octet (BF3) Atoms with more than an octet (SF4) Molecules with an odd number of electrons

(NO) Don’t sweat the exceptions for the regents

Electronegativity Property of an element that indicates

how strongly an atom of that element attracts electrons in a chemical bond

When one atom is SIGNIFICANTLY MORE EN than another, the covalent bond is POLAR.

2 atoms, in a bond, with SIMILAR ENs are NONPOLAR

KNOW EN TRENDS!!! Remember F is the biggest (EN=4.0)

Bond Type by Electronegativity

Electronegativity Difference

Less than or equal to 0.4

Between 0.4 and 2.0

Greater than or equal to 2.0

Bond TypeNonpolar covalent

Polar covalentionic

Naming Chemical Compounds

Chemists name a compound according to the atoms and bonds that compose it

Naming Ionic Compounds

Write cation firstNo need to specify

number of atoms (AKA no prefixes)

Ex. KI (potassium iodide)Ex. KNO3 (potassium nitrate)Ex. CuSO4 (copper(1) oxide)

Naming Molecular

Compounds

Know numerical prefixes

Suffix –ide is added to the atom with a greater EN

Ex. NO2 (nitrogen dioxide)

Ex. BF3 (boron trifluoride)

Ex. P2O5 (diphosphorus pentoxide)

THE END“Good Luck.. Do Well!!!!”