Earth Science

Mrs. HarrisSept.29th 2010

• So… a proton, an electron, and a neutron are out having dinner…

Today:

• Bonds!– Ionic– Covalent

– Game show!

Mini Review

What we know:• Atoms are simplest form of

matter• Atoms of an element are the

same• Atoms are made of protons,

neutrons, & electrons in equal proportions under regular circumstances

• Protons are positive, electrons are negative

What we’re going learn• How atoms can combine• How compounds are held

together• What happens when sub-

atomic particles change in an atom

Drawing AtomsThe protons and neutrons are in the nucleus.

The atomic number tells us how many protons there are (so that means it’s the same number of neutrons and electrons under normal conditions).

Use the periodic table to find out how many protons an oxygen atoms has.

Drawing AtomsThe protons and neutrons are in the nucleus.

The atomic number tells us how many protons there are (so that means it’s the same number of neutrons and electrons under normal conditions).

Use the periodic table to find out how many protons an oxygen atoms has.

Electrons are drawn on electron shells. The rule to drawing them is that the first one holds 2 electrons, the next shell holds up to 8, and the shell after that can hold up to 8.

Here’s the deal

• Atoms that have only a few spaces left really like to fill those empty seats… like a concert!

• Atoms that only have a few electrons in their outer shell have a hard time hanging on to them… like a bad concert where people leave!

So when atoms get together:

• Sometimes they steal electrons– This is an ionic bond– An ion is an atom with a charge (+ or -)– Comes apart easy in water usually

• Sometimes they share electrons– This is a covalent bond.– This is the strongest bond.

Ionic Bond: Let’s try drawing salt!

• NaCl (sodium chloride) • I need to know what Na (sodium) looks like.• I need to know what Cl (chlorine) looks like.

Do you know what will happen?

One molecule of sodium chloride.

Covalent Bond: Let’s draw water!

• H2O (dihydrogen oxide)• I need to know what oxygen looks like.• I need to know what hydrogen looks like.

Sharing is Caring

Equal sharing: nonpolar

Unequal sharing: polar

Any questions on bonds?

Polar, covalent, electron, ionic, nonpolar, neutron, proton, atomic

Why we rely on protons

• Sometimes an atom can have a different number of neutrons

• These are called isotopes• Very common one is C14

14

6

12

6

Game Time!

Next week:

• Minerals

• Live lab!