Chemical Bonding Basic Concepts

(Review) What is an electron? Subatomic particle Carries a negative one charge Each element has a specific, set amount of electrons Follows the trends on the atom’s position on the periodic table

Valence Electrons Valence electrons are contained on the outermost shell of the atom Valence electrons are important in determining how an element reacts chemically with another element The number of valence electrons of an element is determined by its periodic table group (vertical column) in which the element is categorized

Valence Electrons Cont. Group Electron Configuration Valence Electrons 1A, Sodium (Na) 1s22s22p63s1 1 2A Examples: 3A 4A

Valence Electrons Cont. Group Electron Configuration Valence Electrons 5A Examples: 6A 7A 8A

Valence Electrons Cont. Find the amount of valence electrons for each element and state which group they belong to Cesium Barium Oxygen Boron Neon Carbon Chlorine

Chemical Bonding What is chemical bonding? Introduction to the types of bonding: A chemical bond is a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together when atoms bond, their valence electrons are redistributed in ways that make the atoms more stable

Chemical Bonding Cont. There are two types of chemical bonds Chemical bonding that results from the electrical attraction between large numbers of cations and anions is called ionic bonding in this type of bonding, atoms completely give up their electrons to other atoms

Chemical Bonding Cont. Covalent Bonding Atoms joined by covalent bonding share electrons. Covalent bonding results from the sharing of electron pairs between two atoms How is this different from ionic bonding?

Electronegativity Electronegativity, is a chemical property that describes the ability of an atom to attract electrons (or electron density) towards itself in a covalent bond. Follows the trends of the periodic table Increases left to right and bottom to top Fluorine is the most electronegative atom at 4.0

Electronegativity Cont. Common numbers you should know: F 4.0   H 2.1 C 2.5 N 3.0 O 3.5   Na 0.9 S 2.5 Br 2.8 Cl 3.0     K 0.8

Electronegativity Cont.

Electronegativity in Bonding The importance of electronegativity in determining chemical bonding 1. If the electronegativity difference is less than 0.5, then the bond is non polar covalent. 2. Between 0.5 and 1.7, the bond is considered polar covalent 3. If greater than 1.7, then the bond is ionic.

Types of Bonding Let’s go through a visual tutorial Chemical Bonding Tutorial After you’re done, answer the questions at the end of the tutorial Next class we will go over the meanings of covalent bonds