Physical Science
Ions and chemical bonds (ionic bonds and covalent bonds)
Essential Vocabulary
Define the following terms:
Ion
Ionization
Cation
Anion
Chemical bond
Covalent bond
Ionic bond
Diatomic element
Lewis dot
Recall valence electrons
How to use Lewis Dot Notation
•Use the chemical symbol of the element.
•The dots represent the number of valence electrons (group #).
•Only 2 dots can be on each side.
•Always start with 1 dot on each side before pairing up dots.
•Does not matter which side you start pairing.
•Looking at Nitrogen’s lewis dot structure do you think nitrogen will want to lose 5 electrons or gain 3 to get a full outer shell of electrons? Which would be easier?
Practice together
Calcium
Nitrogen
Krypton
Barium
Magnesium
Fluorine
Helium (the only exception to the rules)Your turn
Complete the lewis dot structure for the following elements:
Aluminum
Sodium
Oxygen
Neon
Carbon
Potassium
Ion
Atoms that gains or loses electrons.
Positive ions lose electrons ~ less electrons than protons
Negative ions gain electrons ~ more electrons than protons
Cation
Cations are Positive
(the t looks like a +)
Loses electrons
Metals (left side of periodic table)
Anion
Anions are Negative
(the n stands for -)
Gains electrons
Non-metals (right side of periodic table)Chemical bonds
Bonds between atoms are created when electrons are paired up by being transferred or shared.
A compound is formed when two or more kinds of atoms are bound together chemically.
Two kinds of chemical bonds:
ionic
covalent
Ionic bonds
Electrons are given up by the metal and taken by the non-metal.
Their opposite charges cause them to remain close together.
Usually between a metal (cation) and a non-metal (anion)
Covalent bonds
Electrons are shared between the two atoms.
Stronger bond than ionic.
Usually between two non-metals.