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Physical Science Chapter 18 – Properties of Atoms & the Periodic Table The Elements: Forged in Stars The Origin of the Elements.

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Presentation on theme: "Physical Science Chapter 18 – Properties of Atoms & the Periodic Table The Elements: Forged in Stars The Origin of the Elements."— Presentation transcript:

1 Physical Science Chapter 18 – Properties of Atoms & the Periodic Table The Elements: Forged in Stars The Origin of the Elements

2 Chemical Symbols Abbreviations for chemicals Punctuation is KEY –Capital Letters –Subscript –Superscript –Spacing Elements –ALWAYS Start with a capital letter –Symbols can be 1,2 or 3 letters –First letter is capitalized and 2 nd & 3 rd are lowercase Atom- smallest piece of matter that has the properties of the element CO doesn’t equal Co –CO = Carbon monoxide –Co = Cobalt

3 Atomic number Always the smaller of the 2 # Always a whole # (no decimals) = number p+ Atomic mass Always the BIGGER of the 2 # Usually a decimal = # p+ & n

4 The subatomic particles p+ = positive charge nucleus n = no chargenucleus e- = negative chargecloud Electrons have such a small mass compared to protons and neutrons we say electrons have no mass – but really they do. p+ = 1 amuamu – atomic mass unit n = 1 amu1/12 of a Carbon -12 e- = 0 amu

5 QUARKS Murray Gell-Mann found the name "quark" in the book "Finnegan's Wake" by James Joyce. The line "Three quarks for Muster Mark..." Gell-Mann received the 1969 Nobel Prize for his work in classifying elementary particles. QuarkSymbolSpinCharge UpU1/2+2/3 DownD1/2-1/3 CharmC1/2+2/3 StrangeS1/2-1/3 TopT1/2+2/3 BottomB1/2-1/3

6 Finding the Quark Can you figure out which cork stands for which quark? Fermilab – National Particle Accelerator Lab Chicago IL To Find a Quark- accelerate charged particles to high speeds and cause them to collide with protons, which breaks the proton apart EXTRA CREDIT: Find out what a neutrino is & why it’s important to SD Quarks: Inside the Atom

7 Atomic Models Models- used to help you understand something too large or too small to see Democritus – indivisible atom 450 BC Dalton- atoms are just spheres John Thomson – Plum Pudding model 1904 Discovered the electron 1897 – cathode ray tube- Plum Pudding model- atoms had small negatively charged particles- electrons- embedded throughout a positively charged sphere- INCORRECT BECAUSE- electrons are in clouds AROUND the nucleus, not within the nucleus. Also- did not distinguish between protons and neutrons.

8 Models of the Atom over time

9 Models of Atoms Ernest Rutherford – Rutherford model Gold Foil experiment – positive nucleus (protons) -Almost all the mass of an atom was in the central atomic nucleus surround by electrons. INCORRECT BECAUSE- did not distinguish between protons and neutrons. Chadwick – discovered the neutron 1932 Niels Bohr – Bohr model Electrons traveled in fixed orbits around the nucleus. The nucleus contained protons and neutrons. INCORRECT BECAUSE- electrons are not in fixed orbits but in a region around the nucleus- just occur more frequently in certain places.

10 Electron Cloud Model- Current Model Electron cloud model –Protons and Neutrons in the nucleus –Electrons in an electron cloud- the area around the nucleus of an atom where electrons are most likely to be. Very large compared to the nucleus


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