1. ATOMS

2. Matter is anything that has _______ and takes up ________. mass space rocks soil water bear air trees What is all this? Matter

3. There are many ________________. All matter is composed of ___________.elements different elements

4. Elements are composed of ______. atoms An atom is the____________________________ that retains the chemical identity of the element smallest particle of an element

5. Example: Aluminum is anelement. There are many different elements.

6. Aluminum, Al Cut…cut…cut One atom of aluminum, you have the element aluminum. Imagine you had super powers….. and you are able to cut the tiniest piece of aluminum and still have aluminum… you would have one atom of aluminum.

7. How big is an atom? WOW, that’s small! A piece of aluminum foil contains billions of atoms of aluminum. Aluminum foil is about 200,000 atoms thick! Atoms are extremely small.

8. Aluminum, Al Every atom of aluminum is identical. Atoms of the same element are identical.

9. The atoms of different elements are different! An atom of helium An atom of beryllium

10. How are these atoms different? An atom of helium An atom of beryllium How are these atoms similar?

11. There are many different atoms but all atoms are made up of the same type of subatomic particles.

12. Atoms are made of three kinds of subatomic particles: Protons are ____________________subatomic particles found in the ________. Neutrons are ___________ subatomic particles found in the _________. Electrons are ___________________subatomic particles that ___________________. positively charged (+1) (-1) nucleus neutral (0) nucleus negatively charged orbit the nucleus

13. An Atom proton neutron electron nucleus

14. Mass of a neutron = 1.675 x 10 -24 g Mass of an electron = 9.11 x 10 -28 g Mass of a proton = 1.673 x 10 -24 g

15. Electrons have very little mass when compared to protons and neutrons. An electron is 1/1840 the mass of a proton. Each proton has a mass of about 1840 times that of an electron. Comparison: elephant :: chihuahua Protons and neutrons have the same mass.

16. Therefore, most of the mass of an atom is in the nucleus(99.97%). As a result, the atom consists of mostly empty space with an extremely small solid nucleus. The nucleus is the area in the center of the atom that contains protons and neutrons (positive charge).

17. Generally, particles that have the same electric charge repel each other. Not so for protons. When two protons are extremely close to each other, there is a strong attraction between them. These short-range force of attraction between proton-proton, neutron-neutron, and proton-neutron are called nuclear forces.

18. 5.Chemical reactions occur when atoms are separated, joined, or rearranged. Dalton’s Atomic Theory (1808): 1. All matter is composed of extremely small particles called atoms. 2. All atoms of a given element are identical. The atoms of any one element are different from those of any other element. 3.Atoms cannot be created, divided into smaller particles, or destroyed. 4.Different atoms combine in simple whole-number ratios to form compounds.