Atoms and Elements

By Jose Andres Hernandez-Godoy and Mr. Lin

Atomic Vocabulary

• Ion: A charged atom. Not neutral. There is either more electrons than protons or more protons than electrons. This does not change the element because the same amount of protons exist. – Hydrogen with one proton and one electron is neutral

but is not stable. A stable Hydrogen will have two electrons, making it a negative ion.

• Isotope: An atom with more or less neutrons. As a result, the atomic mass is affected, but not its atomic number.

NN

P

P

e

e

This is an example of Helium (He).

Its atomic mass is 4.002 AMU

2 Protons = 2 AMU2 Neutrons = 2 AMU

The remaining 0.002 referto the mass of the electrons

2

He4.002

3

Li6.941

P

P

P NN N

e

e

e

This is an example of Lithium (Li).

Its atomic mass is 6.941 AMU

3 Protons = 3 AMU3 Neutrons = 3 AMU

The remaining 0.941 referto the mass of the electrons

P

5

B10.811

PP

PPN

N

NN

N

e

e

e

e

e

This is an example of Boron (B)

Its atomic mass is 10.811 AMU

5 Proton= 5 AMU

5 Neutrons = 5 AMU

The remaining 0.811 referto the mass of the electrons

P

1

H1.00794

This is an example of Hydrogen (H)Its atomic mass is 4.002 AMU

1 Protons = 1 AMU0 Neutrons = 0 AMU

The remaining 0.00794 referto the mass of the electron

e

Atoms

• Protons: Positive charge

• Electrons: Negative charge

• Neutron: No charge

• Nucleus: Middle clump of protons and neutrons.Image Courtesy of

http://tharkad.pa.msu.edu/~asteiner/wp-content/uploads/atom_model_03.gif

P

P

PP

P

N

NN

N

N

N

6

C12.0107

e

e

e

e

e

e

This is an example of Carbon (C)

Its atomic mass is 12.0107 AMU

6 Proton= 6 AMU

6 Neutrons = 6 AMU

The remaining 0.00674 referto the mass of the electrons

P

Stable Atoms

• An atom will be stable if only its outer shell is completely full.– Hydrogen is not stable because it has only one

electron in a shell that can hold up to two electrons.– Lithium is not stable because it has only 1 electron in

an outer shell that can hold up to eight electrons.

• Hydrogen would typically like to gain an electron to fill up its outer shell.

• Lithium would typically like to lose an electron to have a full outershell.

Ionic Bond

• When a Hydrogen atom meets a Lithium atom, the Lithium atom will lose its outer electron to the Hydrogen.– Neither atom will have a neutral charge.

• Hydrogen will have a negative charge now because it now will have more electrons than protons.

• Lithium will have a positive charge now because it now will have more protons than electrons.

• The next slide demonstrates an ionic bond

P

e

P

P

P NN N

e

e

e

P

e

P

P

P NN N

e

ee

I’m stable!

Me too!

Covalent Bond

• When two atoms share possession of electrons, they bind in a covalent bond.

• When two Hydrogen atoms meet, neither want to give up an electron, but both would like to gain an electron.– As a result, they will “share” their electrons.

P

e

P

e

P

e

P

e

We Are Stable

Together!