The Atom Survey The Atom Notes Periodic Table Identification Agenda Targets Survey The Atom Notes Periodic Table Identification Identify the process in which the atom evolved through science. Locate parts of the periodic tables. Metals, non-metals,

What is the atom? Atom Democritus, 460 B.C., a philosopher Smallest particle of an element that retains its identity in a chemical reaction Democritus, 460 B.C., a philosopher First to suggest atoms exist Main thought Atoms were indivisible and indestructible Lacked scientific support Democritus helped pave the way to what we know about the atom now

John Dalton English chemist and schoolteacher Took Democritus’ ideas and used experimentation to help back them up Came up with Dalton’s Atomic Theory All elements are composed of tiny indivisible particles called atoms Atoms of the same element are identical. Atoms of different elements are different. Atoms of different elements can physically mix together or can chemically combine in whole numbers to form compounds. Chemical reactions occur when atoms are separated, joined, or rearranged.

How big is an atom? Very, very small Lets take a copper penny So what? Has 24,000,000,000,000,000,000,000 (sextillion) atoms in it! Earth’s population 7,000,000,000 people So what? Take 100,000,000 copper atoms side by side How big would that be? 1 cm long! How do we know they exist? Scanning tunneling microscopes

Copper

Iron

Carbon Monoxide Man

Subatomic Particles Atoms can be broken down Called subatomic particles Electron Protons Neutrons

Electrons Discovered by J.J. Thomson in 1897 Negatively-charged particles His experiment Invented the cathode ray tube Noticed that positively-charged magnets attracted the cathode ray Negatively-charged magnets deflected it Called the particles that made up the cathode ray corpuscles Later called electrons Have 1 negative charge per electron Mass 1/1840 the mass of a proton

Protons and Neutrons Protons Neutrons Discovered in 1886 by Eugen Goldstein Noticed that some particles went the other way in the cathode ray tube Called them protons Mass 1840 times the mass of an electron Neutrons Discovered in 1932 by James Chadwick Have no charge Neutral

The Atomic Nucleus We know that all these particles exist How are they joined together? Ernest Rutherford (1911) answered that Gold Foil Experiment Shot Helium atoms that lost both electrons at a piece of gold foil Expected all the particles to pass through the gold foil What happened? Most passed through Some were deflected at large angles Some came straight back What Rutherford concluded from this Atoms are mostly empty space Most of the mass is concentrated in the middle (positively charged) He called it the nucleus Atomic Model we accept today Nucleus is composed of protons and neutrons Electrons occupy a space around the nucleus

Locating parts of the periodic table Color in and Make a Key Color suggestions Alkali Metals Yellow Alkaline Earth Metals Pink Transition Metals Blue Halogens Purple Noble Gases Light Blue Metalloids Green Rare Earth metals (Lanthanoids & Actinoids) Gray Metals Outline in blue Non-Metals Outline in Red State @ 295* Kelvin (room Temp) Over line in Blue Liquids Over line in Red Gases Circle the diatomic elements- you’ll have to google this. Label direction of groups and periods Draw in stairstep line – dark