1. Bell Ringer THINK BACK TO LAST CLASS & The History of the Atom! WITHOUT using your notes match the scientist to the correct statement that describes his work. Ernest RutherfordJ.J. ThomsonSchrodinger & Heisenberg John Dalton Democritus Niels Bohr 1. _______________________________ proposed that all matter is made up of tiny particles called atoms (from the word that means "indivisible.") 2. _______________________________ suggested that electrons travel in well-defined paths. 3. _______________________________ discovered that atoms have electrons and thought that they were embedded in positively charged material. 4. _______________________________ proposed that matter is composed of atoms and the atoms of an element are identical. His Atomic Theory suggested that atoms can be thought of as being much like a small uniformly solid ball. 5. _______________________________ concluded that there is a small, dense, positively charged nucleus. 6. ______________________________ proposed that electrons travel in electron clouds.

2. Unit 3: Chemistry. Introduction to Atoms. How big is an atom? On average the diameter is 0.00000003 cm!

3. Unit 3: Chemistry. Introduction to Atoms. LET’S WATCH THE TED ED VIDEO! https://www.youtube.com/watch?v=yQP4UJhNn0I LET’S WATCH THE TED ED VIDEO! https://www.youtube.com/watch?v=yQP4UJhNn0I

4. Unit 3: Chemistry. Introduction to Atoms. What is inside an atom? Electrons: are negatively charged particles found in electron clouds outside the nucleus. The Nucleus: is the small, dense, positively charged center of the atom. It contains most of the atom’s mass. The diameter of the nucleus is 1/100,000 the diameter of the atom. Protons: are positively charged particles in the nucleus if the atom. Neutrons: are particles in the nucleus of an atom that have no charge.

5. Unit 3: Chemistry. Introduction to Atoms. Atomic mass unit (amu): the SI unit used to express the masses of particles in atoms Neutron Charge: none Mass: 1 amu Location: nucleus Electron Charge: negative Mass: almost zero Location: electron clouds Proton Charge: positive Mass: 1 amu Location: nucleus

6. Unit 3: Chemistry. Introduction to Atoms. Fun Fact Fun Fact: If it were possible to have a nucleus the volume of an average grape, that nucleus would have a mass greater than 9 MILLION TONS! Fun Fact Fun Fact: If it were possible to have a nucleus the volume of an average grape, that nucleus would have a mass greater than 9 MILLION TONS!

7. Unit 3: Chemistry. Introduction to Atoms. The atom is neutral when there are equal number protons and electrons. If the number of protons and electrons are not equal, the atoms becomes a charged particle called an ion. The atom is neutral when there are equal number protons and electrons. If the number of protons and electrons are not equal, the atoms becomes a charged particle called an ion.

8. Unit 3: Chemistry. Introduction to Atoms. Stop and think… 1)What particles form the nucleus? 2)Explain why atoms are neutral. Stop and think… 1)What particles form the nucleus? 2)Explain why atoms are neutral.

9. Atomic number: the number of protons in the nucleus. This # determines what type of element it is! Atomic number: the number of protons in the nucleus. This # determines what type of element it is! Unit 3: Chemistry. Introduction to Atoms. Atomic mass: the sum of the protons and neutrons in an atom

11. Unit 3: Chemistry. Introduction to Atoms. Isotopes are atoms that have the same number of protons but have different number of neutrons.

12. Unit 3: Chemistry. Introduction to Atoms. Atomic Mass -Number of protons Number of neutrons Atomic Mass -Number of protons Number of neutrons _____ neutrons Calculate the number of neutrons for these carbon isotopes!!!