ATOMS

What are elements made of?What makes up ALL matter?

ATOMS!!

You have 2 minutes to write down everything you know about

atoms!

Draw a circle on your paper.

An atom is the smallest particle into which an element can be divided and

still be the same substance.

Aluminum atoms seen through a scanning tunneling electron

microscope.

What are atoms made of?

• Atoms can be divided into smaller parts called subatomic particles.

1.Nucleus2.Electron3.Proton4.Neutron5.Electron Cloud

Protons

• Protons are positively charged particles in the nucleus.

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Neutrons

• Neutrons are particles in the nucleus that have no electrical charge.

• Neutrons are a little bigger than protons.

No Charge! O

Nucleus

• Every atom has a nucleus, a positively charged center portion.

Inside the Nucleus• Both protons and neutrons are found

inside the nucleus of an atom.

Outside the Nucleus

• Electrons are the negatively charged particles in atoms.

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Electrons are found around the nucleus within electron clouds.

• An atom has the same number of protons as electrons.

This Lithium atom has 3 protons and 3 neutrons.

• If a hydrogen atom has 1 proton, how many electrons does it have?

• If a nitrogen atom has 7 protons, how many electrons does it have?

What Makes Elements Different?

• Atoms make up individual elements. By changing the number of protons in the atom, you change the type of element.

Protons and Electrons are in ALL atoms!

• The simplest atom is made up of just one of each.

1. Draw one proton in the center of the atom (nucleus).

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2. Put one electron in the electron cloud.

3. You just drew a hydrogen atom!

All other atoms have protons, neutrons, and electrons.

1. Draw two protons in the center of the atom (nucleus).

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3. Put two electrons in the electron cloud.

4. You just drew a helium atom!

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2. Put two neutrons in the nucleus.

Ever heard of an ISOTOPE?

• Atoms can have the same number of protons but be missing a neutron or have an extra neutron. That type of atom is called an isotope.

• Isotopes are still the same element. They are

just a little different from every other atom of the same element.

Carbon Isotope

Atomic Number

• The atomic number is the number of protons in the nucleus of an atom.

This Lithium atom has 3 protons, so it has an atomic number of 3.

• Every hydrogen atom has only one proton in its nucleus, so hydrogen has an atomic number of 1.

• Every carbon atom has six protons in its nucleus, so carbon has an atomic number of 6.

Your turn…How many protons are in the nucleus of the

following elements?

1.

2.

3.

4.

Atomic Mass

• The atomic mass is the sum of the protons and neutrons in an atom.

PROTONS + NEUTRONS = ATOMIC MASS

We can determine the atomic mass of an element by looking at the periodic table.

Hydrogen has an atomic mass of 1.00794

Your turn…How many protons and neutrons are in the

nucleus of the following elements?

1.

2.

3.

4.

Let’s Look Closer at Electron Clouds

• There are some rules for drawing atoms: placing electrons in the electron clouds.

Your Turn!

Atomic Number

1.

Atomic Mass

2.

Atomic Mass

3.

Atomic Number

4.

Atomic Mass

5.

Atomic Number

6.