Introduction of an Atom

Molecules and atoms

7th grade unit 3

Atoms are the smellest particles of matter

The idea of a particle of matter so small that it can no longer be cut came from the ancient Greeks. They called this particle "atamos" or indivisible.

Once you get down to a single atom, any further divisions result in subatomic particle. An atom of Carbon (or any element) stops being an element and is now just loose subatomic particles.

subatomic particles

All atoms are made of even smaller particles. They are
Protons- Mass 1amu, + charge
Neutrons- Mass 1amu, 0 charge
Electrons- No mass, - charge

Multiple Choice

What do we call the center of the atom?

• downtown

• nucleus

• village

• plaza

Multiple Choice

What's in the nucleus of the atom?

• The brain of the atom

• The computer system

• Neutrons and Protons

• Grey Matter

Multiple Choice

What is the mass and charge of an electron?

• no mass, negative charge

• No mass, positive charge

• 1 amu, no charge

• 1 amu, positive charge

Multiple Choice

Where are all the atoms organized?

• In the dctionary

• On the periodic table

• On the map of the worls

There are 118 different kinds of atoms

Each square in the PT contains (top to bottom); the atomic number, the chemical symbol, the atomic mass, and the elements name.

This is the symbol for sulfur. It's atomic number is 16

The atomic mass is the number of protons & neutrons an atom has in its nucleus

This is the symbol for sulfur. It's atomic mass is 32.065 atomic units.
This is the average mass of a sulfur atom.
The proton number is ALWAYS 16. The number of neutrons can vary so different isotopes of Sulfur have DIFFERENT numbers of neutrons.

Multiple Choice

What does the atomic number show?

• Number of electrons

• Number of Protons

• Number of neutrons

• number of molecules

Multiple Choice

What does the atomic mass tell us?

• Sum of protons and neurons

• Sum of electrons and protons

• number of neutrons

• Sum of electrons and protons and neutrons