Daily Science Sept 28 Grab a piece of construction paper and make a new unit tab over pages 30 and 31. The new unit is: ATOMS AND THE PERIODIC TABLE If you want to, draw a line on your table of contents under pages 21 & 22 and pages 29 & 30. That separates the units on your table of contents.

Anchor Phenomenon https://www.youtube.com/watch?v=3wxWNAM8Cso We will use this phenomenon throughout our atoms unit

The Atom Pg. 31

Early Theories There was no experimentation Democritus- atoms are solid, homogeneous, indestructible, and indivisible Aristotle- believed everything was made of either fire, water, earth, or air. John Dalton- all matter composed of atoms; all atoms of one element are identical; atoms can’t be created or destroyed (actually used experiments)

Evolution of the Atomic Theory The electron- discovered by JJ Thomson using a cathode ray tube; Robert Millikan discovered the negative charge JJ Thomson came up with the plum pudding model. An atom was a mass ( pudding) with electrons scattered throughout (plums) Ernest Rutherford discovered the nucleus using the gold foil experiment; said atom is mostly empty space with dense positive nucleus in the middle

Evolution of the atomic theory Rutherford did more experiments and concluded the proton was in the nucleus James Chadwick- discovered a neutral particle in the nucleus called the neutron Atom- smallest particle of an element that still retains that elements properties

What do all the numbers mean?

Atomic Number The atomic number of an element (labeled Z) tells you how many protons there are. On the periodic table, the elements are listed as neutral elements so the number of electrons=the number of protons. Z

Calculating # of neutrons The mass number (labeled A) is the number of neutrons + protons. Mass number=atomic mass rounded to the nearest whole number You can find the number of neutron by subtracting the Atomic number (Z) from the Mass number (A) A-Z = # of neutrons

Abbreviations Proton: p+ Neutron: no Electron: e-

Shorthand notation There is a way to represent atomic number and mass number Steps: 1-start with the element symbol 2- place the mass number on the top left side of the symbol 3-place the atomic number on the bottom left side of the symbol

Al 27 13

https://play. kahoot. it/#/lobby https://play.kahoot.it/#/lobby?quizId=3852d6c2-f0dd-4fcc-b657-234a9ad4660f