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Elements & Atoms
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An atom refresher
Matter is anything that takes up space and has mass.
All matter is made of atoms
Atoms are the building blocks of matter, sort of how bricks are the building blocks of houses.
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An atom refresher
An atom has three parts:
Proton = positive
Electron = negative
Neutron= Neutral
The proton & neutron are found in the center of the atom, a place called the nucleus.
The electrons orbit the nucleus.
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What are elements?
Elements are different types of atoms
To make molecules, you must have elements.
Elements are made of atoms. While the atoms may have different weights and organization, they are all built in the same way.
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More about Elements..
Elements are the building blocks of all matter.
The periodic table is a list of all of the elements that can build matter. It’s a little like the alphabet of chemistry.
The periodic table tells us several things…
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Periodic Table
Atomic Number:
Number of protons and it is also the number of electrons in an atom of an element. 8
Element’s Symbol: An abbreviation for the element. O
Oxygen
Elements Name
Atomic Mass/Weight:
Number of protons + neutrons. 16
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8. Identifying Protons, Neutrons and Electrons #112
Atomic # =
Atomic Mass=
Element’s Name= 12 Mg 24
Magnesium
Magnesium 24
Protons=
Electrons=
Neutrons= 12 12 12
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9. Identifying Protons, Neutrons and Electrons #218
Atomic # =
Atomic Mass=
Element’s Name= 18 Ar 40
Argon
Argon 40
Protons=
Electrons=
Neutrons= 18 18 22
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10. Identifying Protons, Neutrons and Electrons #39
Atomic # =
Atomic Mass=
Element’s Name= 9 F 19
Fluorine
Fluorine 19
Protons=
Electrons=
Neutrons= 9 9 10
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Atom Models
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Atom Models
There are two models of the atoms we will be using in class.
Bohr Model
Lewis Dot Structure
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Bohr Model
The Bohr Model shows all of the particles in the atom.
In the center is circles. Each circle represents a single neutron or proton. Protons should have a plus or P written on them. Neutrons should be blank or have an N.
In a circle around the nucleus are the electrons. Electrons should have a dot for each electron - 2P 2N -
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14. Electrons have special rules….
You can’t just shove all of the electrons into the first orbit of an electron.
Electrons live in something called shells or energy levels.
Only so many can be in any certain shell.
The electrons in the outer most shell of any element are called valance electrons.
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Nucleus
1st shell
2nd shell
3rd shell
8 electrons
Adapted from
4th energy level – holds 18
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So let’s try it….
How to draw a Lithium atom
First, look at the Periodic Table
Second, determine the number of protons the atomic number)
Then determine the number of neutrons (Atomic mass – atomic number)
Then determine the number of electrons the atomic number) 3 Li
Lithium 7
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Protons = 3
So let’s try it….
Electrons= 3 3 Li
Lithium 7 3P 4N
Electrons =
2 in the 1st shell, 8 in the 2nd shell
Neutrons = 4
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Protons = 17
So let’s try it….
Electrons=17
17P
18N
Electrons =
2 in the 1st shell, 8 in the 2nd shell
Neutrons =18
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Protons = 6
Electrons= 6 6 C
Carbon 12 6P 6N
Electrons =
2 in the 1st shell, 8 in the 2nd shell
Neutrons =6
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Lewis Dot Structure
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Lewis Dot Structure + -
The Lewis Dot Structure is a bit different from the Bohr model.
It only shows the element symbol and it’s outer most electron shell (Valence Electrons). • • • O • • •
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How to…
Write the symbol.
Start on the right hand side, working your way clockwise around the symbol.
Try Lithium • Li
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How to… • • • N • •
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How to… • Na
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How to… • • B •
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How to… • • • S • • •
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How to… • • • Cl • • • •
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