ATOMS

Atom

Smallest part of any element that contains all properties of that element.

Nucleus

The center of an atom. It contains two particles: neutron and proton. Has a positive charge.

3 main subatomic particles are the proton, neutron and electron.

THESE particles are SMALLER than an atom.

***LOOK at the difference in size!!! WOW…an electron is SO SMALL!!!

Proton

Positively charged particle found in the nucleus.

Neutron

Particle in the nucleus of an atom that does not have a charge. It is a neutral particle.

Electron

Particle orbiting the nucleus of an atom. It has a negative charge.

Valence Electrons – the electrons in the outermost energy level/shell of an atom; they determine how an element will react with other substances.

represents the number of protons found in the atom’s

nucleus.

The sum of the number of protons and neutrons found in the nucleus of the atom for that element.

Protons + Neutrons=Mass Number

Mass Number

6

C

Carbon

12.011

Atomic Number

SymbolElement Name

Atomic Mass

Number of Protons

Equals

Number of electrons

This is what gives the atom a neutral charge.

ATOMIC MASS

The average mass of one atom of an element.

(atomic mass unit)- the SI unit for the masses of particles in an atom.

The Big Picture!

Proton

Electron

Neutron

How many neutrons does an atom contain if its atomic mass is 65 and it contains 30 protons?

Protons + Neutrons

=

?

Protons + Neutrons

= Mass Number

Atom

What is the smallest part of any element that contains all properties of that element?

Subatomic

Particles

What are the particles that are smaller than an atom called?

What are the 3 main subatomic particles that make up an atom?

Proton

Neutron

Electron

Nucleus

What is the center of an atom called?

What are the two particles found in the nucleus of an atom?

Proton

Neutron

and

What type of charge does the nucleus of an atom have?

Positive

Proton

What is the positively charged particle found in the nucleus?

The subatomic particle that is neutral is the

Neutron

Electron

What is the negative charged particle that orbits the nucleus of an atom?

Why does the atom have a neutral charge?

The number of protons in the nucleus of an atom equals the number of electrons orbiting the nucleus.

How do we determine the number of electrons in an atom?

Number of electrons equals the number of protons.

The element chlorine has an atomic number of 17, it has

_____ protons in its nucleus.

17

Mass

Number

Practice

How many protons does an atom have if its atomic mass is 12 and it has 6 neutrons?

What is the mass number if an atom has 2 protons and 2 neutrons?

Which element has an mass number of 12 and contains 6 neutrons?

37