1. Atomic Structure & Elements

2. Size of the Atom ► Average sized atom 0.00000003 cm ► Aluminum foil 50,000 atoms thick ► 1 penny 20,000,000,000,000,000,000,000 atoms of copper and zinc (20 thousand billion billion

3. Parts of the Atom ► Proton- Positive (+) particle (nucleus) ► Determines the element ► Neutron- Neutral (0)particle (nucleus) ► Nucleus- Central, dense core of atom  Protons and neutrons are found in the nucleus of the atom and make up almost all the mass of the atom. ► Electron- Negative (-) particle (electron cloud around nucleus)

5. Modern view of the atom ► The atom is mostly empty space ► Nucleus – Protons and neutrons ► Electron cloud is the area where electrons of an atom are most likely found.

6. Counting the Pieces Review ► Atomic Number= Number of protons ► Atomic Mass= Protons + Neutrons ► # of protons determines kind of atom. ► Neutral Atom= the same number of protons and electrons ► All particles in the atom have mass. ► Proton= 1amu (atomic mass unit) ► Neutron= 1amu ► Electrons have a very small mass

7. Atoms and Elements ► Atoms of different elements are different  Determined by # of protons ► Atoms of the same element are almost the same  Isotopes have a different number of neutrons  Does not change the charge of the atom.  Occur naturally and share the same properties  Some are unstable and the nucleus can change composition (radioactive isotopes)

8. Isotope

9. Naming the Isotopes ► 3 2 He ► 4 2 He ► 12 6 C ► 14 6 C ► 235 92 U ► 239 92 U Mass number of this atom Atomic number of the element This atom of hydrogen has two protons and one neutron. 1 + 1+ 1= 3 amu Atomic Mass Atomic Number Element Symbol

10. Write the isotopes of Hydrogen shown. 11H11H 21H21H 31H31H

11. Atomic Mass ► The atomic mass is not a whole number because it is a weighted average of all the oxygen isotopes in the world.

12. Measuring Atomic Mass ► Atomic mass is measured in Atomic Mass Units or AMU’s and is the addition of the number of Protons and Neutrons in an atom. Same number of electrons & Protons Neutrons different. Atomic Mass=________

13. Elements Chapter 4 Section 1

14. ► An element is a pure substance that cannot be broken down into simpler substances and have the same properties ► Classified by properties ► Grouped into categories using these properties ► Metals ► Metalloids ► Non-metals

15.  Metals  Shiny  Good conductors of thermal energy  Good conductors of electrical current  Malleable  Ductile  Located on the left side of the periodic table Three Categories of Elements

16.  Nonmetals  Dull  Poor conductors of thermal energy  Poor conductors of electric current  Brittle/ unmalleable  Located on the right side of the periodic table Three Categories of Elements

17.  Metalloids  Sometimes called semi-metals or semiconductors  Can be shiny or dull  Somewhat malleable  Somewhat ductile  Some are good conductors of thermal energy and electrical current Three Categories of Elements