Atomic Structure

Atomic Structure:

• Location: Where it is on the atom

• Charge: Electric charge (positive, negative or neutral)

• Mass: how big or small it is

Parts of the Atom:NUCLEUS

• The small center part of the atom that contains the neutrons and protons

• from Greek “karyon”, meaning kernel • Protons and neutron are

packed very tightly! • The density is the same

as having the entire mass of the sun squeezed into Chicago!

Parts of the Atom:ELECTRON CLOUD

• The large region around the nucleus that contain the traveling electrons

• 100,000 times larger in diameter than the nucleus!

• Impossible to determine the exact location of an electron within the cloud.

Parts of the Atom:PROTON

• Location: the center of the atom

PROTON

From Greek “Protos” meaning first

From suffix “ion” meaning subatomic particle

• Charge: positive

• Mass: About 1 a.m.u, almost 2000 times larger than the electron, slightly smaller than the neutron

Parts of the Atom:NEUTRON

• Location: the center of the atom

NEUTRON

From the noun “neutral”

From suffix “ion” meaning subatomic particle

• Charge: neutral

• Mass: about 1 a.m.u., almost 2000 times larger than the electron, slightly larger than the proton

Parts of the Atom:ELECTRON

• Location: the outer part of the atom, surrounding the nucleus

ELECTRON

From the word “electric”

From suffix “ion” meaning subatomic particle

• Charge: negative

• Mass: almost 0 a.m.u., almost 2000 times smaller than the proton and neutron.

Comparing Locations:Electrons are on the outside of the

atom. They spin around the nucleus in an electron cloud.

The protons and neutrons are packed tightly together in the center of the atom.

The space between the electron cloud and nucleus is huge!

If the nucleus was the size of a golf ball, the electron cloud would be 1.5 miles away!

Comparing Charges:

Electrons have a negative charge, protons have a positive charge and neutrons have no charge.

Comparing Mass:

Electron (so tiny, you can’t see it)

If a proton was the size of the blue sphere on the left, then the electron would be one pixel of the screen—so small, that you can’t see it! Click here to see website showing this.

Protons and Nuetrons are almost 2000 times larger than electrons

Getting Smaller….We now know that matter is made up of even smaller matter:

Particles in various combinations

Quarks Leptons

up

down

charm

strange

top

bottom

electron muon tau

electron neutrino

muon neutrino

tau neutrino

Up and Down Quarks3 quarks (up + up + down) make up a proton 3 quarks (down + down + up) make up a neutron

proton neutron

electron

Bohr Model of a HELIUM ATOM

+N

N

+-

-

proton

electron neutron

Shell

Question: What are some limitations of this model?

Answer: Electrons are too large and not in an electron cloud, electrons are too close to the nucleus.

ATOMIC STRUCTURE

Particle

proton

neutron

electron

Charge

+ ve charge

-ve charge

No charge

1

1

nil

Mass

nucleus

nucleus

shell

Location

ATOMIC STRUCTURE

Electrons are arranged in Energy Levels or

Shells around the nucleus of an atom.

• first shell a maximum of 2 electrons

• second shell a maximum of 8

electrons

• third shell a maximum of

8 electrons

3rd shellCan hold up to 8 electrons

Adapted from http://www.sciencespot.net/Media/atomsfam.pdf

2nd shellCan hold up to 8 electrons

1st shellCan hold up to 2 electrons

NucleusContains protons and neutrons

Analyzing Elements on the Periodic Table

the number of protons in an atom

the number of protons and neutrons in an atom

Be4

9.012 Atomic Mass

Atomic number

* Number of electrons = number of protons

Beryllium

1, 2 or 3 letters. First letter always capitalized, second always lower case.

Element Symbol

* Number of neutrons = Atomic Mass (rounded to nearest) – Atomic Number

Element Name

Created by G.Baker www.thesciencequeen.net

So let’s try it….How to draw a Lithium atom

First, look at the Periodic Table

Second, determine the number of protons (Look at the atomic number)

Then determine the number of neutrons (Atomic mass – atomic number)

Then determine the number of electrons

(Look at the atomic number)

3

Li

Lithium7

Created by G.Baker www.thesciencequeen.net

3

Li

Lithium7

+

++

Protons = 3

Neutrons = 4

(7-3=4)

-

-

-

Electrons = 3

2 in the 1st shell, 1 in the 2nd shell