Ch 1 Structure and Bonding

2 types of bonding and their descriptions

ionic - formed when there is a transfer of electrons from one atom to another

covalent - formed when a pair of electrons is shared between two atoms

A bond is an ______ force between ____ atoms

attractive, two

Why do bonds form?

to achieve greater stability by allowing atoms to attain a full valence shell of electrons, thereby lowering their potential energy.

The octet rule

states that atoms tend to gain, lose, or share electrons in order to have eight electrons in their valence shell, achieving greater stability.

All inert gases, except this one, have an octet of electrons in their valence shell

Helium

hydrogen and helium require a _____ of electrons

duplet

electron-dot structures vs line-bond structures

Electron-dot structures show valence electrons as dots around atoms, while line-bond structures use lines to represent bonds between atoms, simplifying the representation of molecular structure.

Hydrogen # of bonds

1

oxygen # of bonds

2

Nitrogen # of bonds

3

F, Cl, Br, I form only ___ bond

1

valence electrons that aren’t used for bonding are called

nonbonding electrons or lone-pair electrons

Exceptions

• 3rd and 4th row elements can expand their octets

• BF3 and AlCl3 have an incomplete octet of 6 but are still stable

• the methyl carbocation CH₃⁺ has an incomplete octet and is unstable

• the methyl radical CH₃ has 7 valence electrons and is unstable

• hydrogen acquires a duplet of electrons

3 common structures of organic molecules

tetrahedral, planar, and linear

tetrahedral structure

• pyramid shape

• bond angles of 109.5 degrees

planar structure

• flat, two-dimensional shape

• bond angles of 120 degrees

• 2 carbon atoms linked by a double bond

linear structure

• straight chain arrangement

• bond angles of 180 degrees

• 2 carbons attached by a triple bond