1. Atoms and the Periodic Table Chapter 17

2. Objectives At the end of this lesson, you should be able to: Describe and define atoms and their subatomic particles Describe the relationship between atoms and elements Describe how atoms are held together

3. 17.1-Elements contain a single kind of atom Atoms make up all of the matter around you. To date, there about 120 known distinct atoms about 90 are found in nature

4. 17.1-Elements contain a single kind of atom Element - any material made of only 1 type of atom (ex. gold, nitrogen) All elements are listed in a chart called the periodic table Each element has its own atomic symbol

5. What is an element? A. A material containing 1 or more atoms. B. A material made of only 1 type of atom. C. A material made of 1 or more atoms chemically bonded together.

6. 17.1-Elements contain a single kind of atom Atoms - very, very old Formed @ beginning of the universe Recycled and redistributed over and over

7. 17.1-Elements contain a single kind of atom Atoms - very, very small Can’t be seen w/ visible light Smaller than wavelengths of visible light

8. 17.1-Elements contain a single kind of atom Atoms - made of subatomic particles - electrons, protons, and neutrons Atoms only differ in # of these particles p’s and n’s-bound together to form the atomic nucleus e’s - surround nucleus in an electron shell or electron orbital Can’t pinpoint location of e’s - just know about where they are in shells/orbitals

9. 17.2 - Atoms are mostly empty space e’s move around the nucleus in an atom, but are widely separated from the nucleus ∴, atoms are mostly empty space.

10. Which two subatomic particles can be found in the atomic nucleus? A. Proton and electron B. Electron and Neutron C. Neutron and proton

11. 17.2 - Atoms are mostly empty space Atoms don’t pass through each other because of electrical repulsion Like charges repel - they move away from each other So, atoms can only get so close before they start repelling each other

12. 17.2 - Atoms are mostly empty space How are atoms held together? Electrical forces - forces of attraction or repulsion Protons have a + charge; Electrons have a - charge Opposite charges attract each other - The positively charged nucleus (p’s and n’s) is attracted to the negatively charged electrons, thus holding the atom together.

13. Atoms are held together by the electrical attraction between A. The negatively charged nucleus and the positively charged electrons. B. The negatively charged electrons and the neutrally charged nucleus. C. The negatively charged electrons and the positively charged nucleus.