Particle Pictures! When you brush your hair, especially in the winter, what is something (a little irritating) that can happen? Why do you think this happens? What do you think is usually true for your hair – is it overall negatively charged, overall positively charged, or overall neutral? How might this change when you brush it? Charges can be transferred between objects (as you will see in a few more examples...)

Two Plastic Rods

What do you observe?

Two negatively charged plastic rods repel. On your whiteboard, draw a particle picture for ONE of the NEGATIVELY CHARGED plastic rods. For simplicity's sake, you may assume that each atom has only one proton. Each circle in this picture represents one atom (obviously there are more atoms than this in the object).

Particle Pictures How can you represent a neutral atom in one of those circles (assume each atom has just one proton)? How can you represent a negatively charged atom? How can you represent a positively charged atom? Why don't we draw neutrons in our circles that represent atoms?

Big Ideas #1: Like charges repel. #2: An object becomes negatively charged when it gains electrons, so that it has more electrons than protons.

On your whiteboard, draw a particle picture showing the “atomic” level of the two plastic rods as they are brought near each other

Two glass rods: What do you predict will happen?

Two Glass Rods

Two positively charged glass rods repel. On your whiteboard, draw a particle picture for ONE of the POSITIVELY CHARGED glass rods. For simplicity's sake, you may assume that each atom has only one proton

Big Ideas #3: An object becomes positively charged when it loses electrons, so that it has less electrons than protons. Not a big idea but a question to think about... why do you think it's easier for an atom to gain/lose electrons than it is to gain/lose protons and become charged?

On your whiteboard, draw a particle picture showing the “atomic” level of the two positively charged glass rods brought near each other

Plastic and Glass Rod

Big Ideas #4: Oppositely charged objects attract.

On your whiteboard, draw a particle picture showing the “atomic” level of the positively charged glass rod and negatively charged plastic rod brought near each other

HOMEWORK (due Monday): WS 2 (particle pictures for the balloon) for this assignment, each balloon image is SEPARATE (they are not interacting with each other)