1. ATOMS

2. WHAT IS AN ATOM??? LET’S FIND OUT…

3. The smallest particle of an element that has properties of that element is called
the ATOM.
* It is the basic building block of all matter!!

4. An atom that has no charge; it’s neither positive or negative is called a NEUTRAL ATOM.

5. The atom is made up of 3 parts or subatomic particles
The atom is made up of 3 parts or subatomic particles. They are the proton, electron, and neutron.

6. The proton has a positive charge (+), is found in the nucleus, and has a mass of 1.
The neutron is neutral, it is found in the nucleus and has a mass of 1.
The electron has a negative charge, moves AROUND the nucleus, and has a mass of 0.

7. The nucleus is the positively charged center of an atom
The nucleus is the positively charged center of an atom. *Since atoms are neutral, the protons need to balance electrons. Therefore, the number of protons = the number of electrons!! (p’s = e’s)

8. The atomic number is the number of protons in the nucleus of an atom
The atomic number is the number of protons in the nucleus of an atom. For example: Carbon’s atomic number is 6. So, there are 6 protons in the nucleus. Oxygen has an atomic number of 8. How many proton’s are there? 8 How many electrons are there? 8

9. The atomic mass of an atomic number is the sum of protons and number of neutrons.
#p + #n = mass #
#n = mass # - atomic #

10. Because atoms are sooo small, we are unable to see them
Because atoms are sooo small, we are unable to see them. Therefore, scientists make and use models to represent them. There are 2 models for atoms:
Bohr Model: Claimed that electrons moving around the nucleus only travel in orbits like planets thus it was called a planetary model.
Electron Cloud Model: This is the current model we use today and is more accurate. It says that electrons are found in a “cloud” around the nucleus (kind of like the spray of water from a sprinkler, each drop represents where an electron might be.)

12. ATOMS COMBINE
Most matter is in the form of compounds or mixtures of compounds. For example: Salt, water carbon dioxide (exhaled)
Compounds have properties unlike those of their elements. For example: Salt (NaCl)- Sodium/Na is a shiny, soft, gray, explosive metal with water and Chlorine/Cl is a yellowish-green gas that can kill but when they combine, it forms sodium chloride or table salt.

13. A chemical formula tells what elements make up a compound and the ratios of the atoms to those elements. For example: NaCl (salt) means there is 1 atom of sodium (Na) to 1 atom of chlorine (Cl).
A subscript is a number in a chemical formula written after a chemical symbol that tells how many atoms of an element there are in a compound. It means “written below”. For example: H20 (2 is the subscript) There are 2 atoms of Hydrogen and 1 atom of Oxygen. This makes up 1 molecule of water.

14. A chemical bond is a force that holds atoms together in a compound
A chemical bond is a force that holds atoms together in a compound. They use electrons to bond. There are 2 types of bonds.
1. Ionic Bond: The transfer of electrons from one element to another. It is made of charged particles (+ and – atoms). Example Na(+)Cl(-)= Ionic Bond
2. Covalent Bond: The sharing of electrons between elements. It is NOT made of charged particles. Ex: H2O = Covalent Bond