Vocabulary Ion – An atom or bonded group of atoms with a positive or negative charge Cation – A positively charged ion Anion – A negatively charged ion Ionic bond – The electrostatic force that holds oppositely charged particles together in an ionic compound Ionic compounds – Compounds that contain ionic bonds

Vocabulary Electron affinity – the energy of a neutral, gaseous atom when an electron is added to the atom to form a negative ion; the neutral atom's likelihood of gaining an electron Ionization energy – the energy required to remove an electron from a gaseous atom; generally increases in moving from left-to- right across a period and decreases in moving down a group.

Atomic Size Notice the atomic size increases as period increases and decreases and the group increases.

Ionic Sizes Ionic Sizes are different based on whether electrons are added or taken away.

Polyatomic Ions An ion made up of two or more atoms bonded together that acts as a single unit with a net charge Quiz on polyatomic ions on the next slide on Friday

Common Polyatomic Ions (pg. 221)

Formation of Ionic Compounds The charge indicates what ionic compound will form – oxidation number It will always be with one form of cation and one form of anion. Criss-cross Subscripts indicate a ratio Example: Mg 2+ Cl - MgCl 2

Criss-Cross Examples Ammonium dichromate Sodium chloride Calcium oxide

Vocabulary Valence electron – The electrons in an atom’s outermost orbitals; determine the chemical properties of an element. Molecule – Forms when two or more atoms covalently bond Covalent bond – A chemical bond that results from the sharing of valence electrons – “co-” means to share – “-valent” refers to valence electrons

Naming Ionic Compounds Cations retain their names Anions end in “-ide” – e.g. oxygen becomes oxide, chlorine becomes chloride Metals require a Roman numeral to indicate its charge. – e.g. iron (III) oxide. Cation is Fe 3+. Anion is O 2-. The compound is Fe 2 O 3 Polyatomic ions require parentheses if more than one polyatomic ion is indicated. – e.g. ammonium sulfide – NH 4 + and S 2- becomes (NH 4 ) 2 S

Practice Naming Ionic Compounds NaBr CaCl 2 KOH Cu(NO 3 ) 2 Ag 2 CrO 4 NH 4 ClO 4

Naming Covalent Compounds Greek prefixes indicate the number of atoms in each molecule If the first element noted is one, “mono” is left out, e.g. carbon dioxide = CO 2 Mono – oneHexa – six Di – twoHepta – seven Tri – threeOcto – eight Tetra – fourNona – nine Penta – fiveDeca – ten

Naming Covalent Bonds H 2 O SO 2 NF 3 CCl 4 diarsenic trioxide

Lewis Dot Structure This is a representation of an element or molecule showing the valence electrons. The element symbol is used, and dots are placed around it to indicate the valence electrons. Lines are used to show a pair of valence electrons are shared.

Lewis Dot Structure H 2 – Hydrogen H 2 O – Water NH 3 – Ammonia CH 4 – Methane HF – Hydrogen fluoride

You Try PH 3 H 2 S HCl CCl 4 SiH 4

Double and Triple Bonds Oxygen shares two pairs of electrons, so it has a double bond. O 2 Nitrogen shares three pairs of electrons, so it has a triple bond. N 2