The AtomQuick!

Time yourself writing the

numbers from 1000-1050.

Then, multiply the time by

20,000

How small is an atom?A human hair is about 1 million atoms acrossAnd… a million is a lot! It would take you at least 20 days without sleeping (at just over 1-second per number) to count to 1,000,000 out loud.50 million (all the people in Oregon x 12.5 or almost twice the number of people in California)

atoms lined up = 1 cm. In other words, if all of the people in Oregon were atoms & they lined up holding hands, the line would be less than 1mm longIf each atom in a single marble were the same size as a grain of sand, you would end up with enough sand to cover the whole of Oregon with a layer close to a thousand feet (2/3 or a mile) thick.If you walked around the equator of the earth continually without stopping to sleep or eat, it would take about 12,500 hours or 520 days. It's a big place!

If a golf ball could be magnified to the size of the whole earth, most of its atoms would be more or less the size of a golf ball

Atomic Structure

Parts of an Atom

Proton• +1 charge

• In nucleus only

• Mass= 1amu (1.6 x 10-24g)

Neutron• 0 charge

• In nucleus only

• Mass= 1amu (1.6 x 10-24g)

Electron• -1 charge

• Around nucleus- in shells

• Mass= 9.1 x 10-34g (relatively insignificant)

Electrons But… Electrons take up by far

the most space, 10,000 times more than the nucleus

Nucleus = basketball then electrons stretch out in a diameter of 7.5km (all the way to Phil’s Trails, Target, Elk Meadow School- almost)

Nucleus= marble then electrons stretch 100m (size of a football field)

Atomic Structure

Atomic Number = # of protons and # of electrons

Mass number = # of protons + neutrons

Try these…

I have an atomic number of 13

• Aluminum I have an atomic mass of 32

• Sulfur I have 83 electrons

• Bismuth Number of neutrons in Cobalt (Co)

• 32 Have 10 neutrons

• Neon AND Fluorine

But wait!

How many neutrons does Chlorine have?

18.5?

Isotopes= atoms with the same # of protons, but different # of neutrons (and thus different mass)• Ex: sodium-23, sodium-24

• Symbol:Mass

Number

Radioisotopes

Unstable isotopes= radioactive= radioisotopes• Carbon-14 decays into carbon-12 over time

by kicking off neutrons (or parts of neutrons)

Have many uses!• Americium-241= smoke detectors

• Technetium-99= thickness gauges

Back to Chlorine….

Atomic Mass on the periodic table is a weighted average of the atomic masses of all isotopes (see p.119)

Average Atomic Mass = (% of isotope 1)(mass of isotope 1) + (%of isotope 2)(mass of isotope 2) +…

Chlorine = 75.77%(35) + 24.33%(37) = 35.5 amu

So…

What is the most common isotope of Hydrogen?

How about Zinc? Is this the most common Li isotope? Carbon is 98.89% carbon-12 and 1.11%

carbon-13. What’s the average atomic mass?

Hydrogen-1

Zinc-65 Nope

98.89%(12) + 1.11%(13) = 12.011 amu

A couple more…

What’s the most common isotope of gallium?

If element X is 57% X-25, 29% X-26 and 14% X-27, what’s the average atomic mass of X?

Gallium-70

57%(25) + 29%(26) + 14%(27) = 25.57 amu