Remember to make corrections with a RED

pen!Work quietly with your group!

Helium has 2 protons (2+) & 2 electrons (2-), so charges cancel each other

Because water is polar:

B/c they have the same number of protons and electrons (+ and – charges)

Water Molecule

Water is Polar:One end is positive (+), the other end is negative (-)

-

+

Simplified Drawing:

Why? Because water is a polar molecule!

-

It’s attracted to both positive AND negative charges

H

H

O

Why does water bend towards the charged object when the objects have different charges?

Glass is positively charged, so it attracts negative end of water.

Knife is negatively charged so it attracts positive end of water.

- +Water is Polar!

Charged comb (negatively charged)

-

-

-

Comb “steals” electrons from hair and becomes negatively charged.

e-

e-e-

This leaves your hair with an overall positive charge, so hair is attracted to comb because opposite charges attract!

The Van de Graff generator gives off e- and gives your hair negative charges.!

Atom model evolved from a very simple “sphere” to much more complex. Why? Because of new research.

The model has changed from just being a small, indivisible particle to a small particle that also has subatomic particles (protons, neutrons, electrons) and has them in specific places.

INDIRECT b/c scientists can’t “see” an atom. All of their inferences are based on indirect evidence

Atoms have a very small nucleus (center of atom)

Nucleus is positively charged (protons)

Atoms are mostly empty space

1911

Electron Energy Levels

nucelus

1st energy level

2nd energy level

3rd energy level

1999, Addison, Wesley, Longman, Inc.

Energyabsorbed

e- fall back= EnergyReleased (what we see as colors)

= e- jump

Neils Bohr:Bohr Model – showed e- exist ONLY in specific energy levels (shells)

Electrons “falling” from higher (“excited”) to lower (“resting”) energy level.

Energy levels (“orbits”) where electrons cannot go.

Electrons!

Red (=LOW energy, but longer wavelength)

Violet (= HIGH energy, but shorter wavelength)

Some elements have many different e- energy levels, other elements have fewer:

Test is next class.STUDY.Open up the book and read the page, open up the book and get an A….

A little more Chemistry Humor:

Your job right now:• Keep your voices level LOW (good behavior =bonus points if

you win best class!).• Go to public/all/kmchenry folder and go through the

jeopardy with your team. • Rotate through each person-everyone gets to choose a

topic, amount and answer.• Keep doing this rotation-there are 25 questions so

everyone should be able to pick/answer at LEAST 6 questions!

• When finished, go to my website Ch.3/4 links and click Part 1 And Atoms/Bonding Games (4th link down)

• Scroll down & click on “particles of an atom” (pick one of the games and play)~ FIVE MINUTES;

• afterwards, switch people, scroll down on the game page and click on “models of atoms” (pick one of the games and play); FIVE MINUTES

• afterwards, switch people and go back to the Ch.3/4 links and click on the Part 1 Jeopardy Online Practice Review. Play this with your team, taking turns to choose questions and answer (skip the first column called electron configuration). Then repeat for the next online jeopardy