Intro movie

Topic: Intro to Bonding

Do Now: 1. Pick up a new unit packet – Test will be

on Dec. 162. Begin filling in p.3 3. I will be coming around to check Review

Book Assignment 1, don’t forget you have a Review Book Assign due every day this month!

Intermolecular Forces

• Attractive forces between molecules• Determine phase at room temperature• 3 kinds:

– Dispersion– Dipole-dipole– Hydrogen bonding

• These are much weaker than forces within a molecule

Intramolecular Force – forces within a molecule

• A chemical bond is the force that holds two atoms together

• Due to electrostatic forces (charges)• Bonding:

1. ionic bonding: metals and nonmetals2. covalent bonding: nonmetals and

nonmetals3. metallic bonding: metals and metals

So why do atoms bond?!

• Atoms attain a stable valence electron configuration by bonding with atoms.

• All atoms want to be like Noble Gases because they have a stable valance electron configuration (a full octet)

What Noble Gases tell us:

• Do not form compounds under ordinary conditions–= extremely stable

• 8 valence electrons = great stability–also low energy!

Octet Rule: Why Bonds Form• Goal: achieve noble gas electron config.

- want 8 valence electrons (H wants a total of 2)

Why: Low energy, high stability stateHow: Atoms form bonds by:

• gaining• losing, or • sharing electrons

3 Types of Bonding

• Ionic: electrons are transferred

• Covalent: electrons are shared

• Metallic: “sea of mobile electrons”

Energy & Chemical Bonds

Making a bond Releases energy!It’s exothermic!

Energy & StabilityLow Energy means High StabilityHigh Energy means Low Stability

HINCE MY WALL…KEEP CALM (stable) AND FORM A BOND (it releases energy)

A + B AB + energy• bond is formed: energy is released• -AB has less PE than A and B • -AB is more stable than A and B

The greater the energy released when the bond is formed, the more stable the bond is

K + L KL + 400 JoulesReaction2B + C BC + 100 JoulesReaction1

Which product is more stable, BC or KL?

Energy, Charge and Mass are Conserved in Chemical reactions

(when bonds are formed or broken)

Stability in Chemical Systems

• If it exists, its stable!

• Of course, some things are more stable than others!

Quick Quiz

• Elements in the same column have the same ____________________________.number of valence electrons

• Elements with the same number of valence electrons have similar _____________________________.chemical properties