the beginning of matter. an atom is the smallest unit of matter that exists

The beginning of matter

An atom is the smallest unit of matter that exists.electron

neutron

proton

Matter is anything that has mass (weight) and occupies space (volume).

QUESTION…

Is air matter?

Are you matter?

If you are matter…are you made of atoms?

Is everything made of atoms?

Can you see atoms?

Are atoms bigger or smaller than cells?

If we can’t see atoms how do we know they exists?

Mostly empty space!!!

electron

neutron

proton

electron

neutron

proton

Nucleus made of protons and neutrons. All the weight of an atom is HERE!

Different ENERGY LEVELS containing…ELECTRONS

They have NO weight even when there are 400 of them.

electron

neutron

proton

electron

neutron

proton

Proton, neutron, and electron

Each atomic particle (part of an atom) has a size and a charge.

Protons = 1amu positive +Electrons = 0 amu negative --Neutrons = 1amu neutral (both positive and negative ) = 0

#PROTONS = # ELECTRONS (positives = negatives)

#PROTONS = ATOMIC NUMBER (on the periodic table)

#PROTONS + #NEUTRONS = ATOMIC MASS

Difference in Atoms and Molecules

• Atom is a single unit—1---Mg• Molecule is 2 or more atoms chemically

combined. They are given in a formula (H2O)

Element vs. Compound

• Element is on the periodic table. It has 1 capital letter

• Compound is 2 or more elements combined chemically. Will be visible in a formula (H2O)

Compound vs. Mixture

• Both have 2 or more atoms…• Compound is chemically combined and

mixture is physically combined. There is NO formula for a mixture.

How do you find the # of atoms in a formula?

• Look at each element.• Look for a number to the right of the element.– Add them together

If there are NO numbers then it is 1. Add 1

How to find the # of elements in a formula?

• Count the capital letters.• Each element you should have memorized

from our list on the periodic table.

Periodic Table

• The periodic table is an organizational tool to show relationships between elements.

Set up

• The rows are called—periods PR• The columns are called—groups GC

Relationships of periods

• The atomic numbers increase by 1 moving left to right. This is the number of protons THUS the number of electrons

Another relationship

• The atomic mass increases from left to right but not by a specific amount because it is the number of protons + the number of neutrons

Relationship of Groups

• The groups have the same number of electrons in the outer shell.

• This gives them similar chemical properties because it is the electrons in the outer shell that allow bonding.