Notes: Ionic Bonds and Lewis Dot Structures

How to Draw Lewis Structures

Lewis Structures Find your element on the periodic table. Determine the number of valence electrons. This is how many electrons you will draw.

Lewis Structures Find out which group (column) your element is in. This will tell you the number of valence electrons your element has. You will only draw the valence electrons. www.chem4kids.com

Groups - Review Group 8 = 8 electrons Group 1 = 1 electron Except for He, it has 2 electrons Group 2 = 2 electrons Each column is called a “group” 3, 4, 5, 6, 7 Each element in a group has the same number of electrons in their outer orbital, also known as “shells”. The electrons in the outer shell are called “valence electrons” www.chem4kids.com

C Lewis Structures Write the element symbol. Carbon is in the 4th group, so it has 4 valence electrons. Starting at the right, draw 4 electrons, or dots, counter-clockwise around the element symbol. C

C Lewis Structures Check your work. Using your periodic table, check that Carbon is in the 4th group. You should have 4 total electrons, or dots, drawn in for Carbon. C

C Lewis Structures On your worksheet, try these elements on your own: P Ca Ar Cl Al C

Ionic Bonds

Bonding Atoms Why do atoms bond? - each atom wants a full outermost energy level - gain, lose, and share valence electrons to achieve the duet or octet rule aka: “being happy” - gives each atom an electron configuration similar to that of a noble gas ex. Group 18: He, Ne, Ar

Chemical Bonds Chemical Bonds - attractive force that holds atoms or ions together - 3 types ionic, covalent, metallic - determines the structure of compound - structure affects properties - melting/boiling pts, conductivity etc.

Ionic Bonds / Ionic Compounds Definition - bond formed by the attraction between oppositely charged ions cation: positive: lost e-’s anion: negative: gained e-’s - oppositely charged ions attract each other and form an ionic bond ex. Na+ + Cl- = NaCl - electrons are transferred from one atom to another - negative ions attract more positive ions, and soon a network is formed

Networks / Crystal Lattices - repeating pattern of multiple ions ex. NaCl - every Na ion is next to 6 Cl ions - strong attraction between ions creates a rigid framework, or lattice structure: aka: crystals ex, cubes, hexagons, tetragons

Properties of Ionic Compounds Structure affects properties - strong attractions between ions: strong bonds - high melting/boiling pt - shatter when struck (think of it as one unit) - conductivity solid: ions are so close together, fixed positions, (can’t move) NO conductivity liquid: ions are freely moving due to a broken lattice structure Good conductivity