How did Rutherford conclude that he found a positive nucleus? Drill How did Rutherford conclude that he found a positive nucleus?

Agenda Notes about Atoms Drill Build an atom simulation HW Handout Post Test Notes about Atoms HW

Build an Atom Simulation Google “phet build an atom” Complete the handout Complete the Post Test Place in bin Start to work on Review Packet! 

Atoms Atomic Number Periodic table is arranged in increasing atomic number Equals the number of protons in the atom Used to identify the atom Every atom of an element will have the same atomic number and thus the same proton number

Review How can you find the number of protons? Find the element’s atomic number on the periodic table Practice: Identify the number of protons Cr Li

Review How can you find the element from the number of protons? Find the atomic number on the periodic table Identify the element 13 protons 2 protons

Check In How many protons does Oxygen (O) have? 8 16 6 76

Isotopic Notation Isotopes Atoms of the same element (same protons) with different masses due to having different neutrons amounts

Isotopic Notation A = mass number Z = atomic number X = element symbol

Element – Y Y = mass number

Mass Number Mass Number = Protons + Neutrons If you know any two pieces of the equation, you can solve for the third

Review How can you find the number of neutrons? Find mass number: Mass number – protons Find the number of neutrons: Zinc-65 Oxygen-16 Find the mass number: Boron, 6 neutrons 7 protons, 7 electrons, 5 neutrons

Check In How many neutrons does Chlorine – 37 have? 17 35 37 20

Atomic Charge In neutral atoms, electrons = protons Electrons are negative If you gain electrons, you increase the atom’s “negativity” and the charge becomes more negative Add 2 electrons, charge = -2

If there is a charge, this is known as an ion If you lose electrons, you decrease the atom’s “negativity” and the charge becomes more positive. Take away 1 electron, charge = +1 If there is a charge, this is known as an ion

Find the charge 3 protons, 2 electrons = 8 protons, 10 electrons =

How many electrons? Ca+2 P-3

Check In How many electrons does Se-2 have? 34 36 78 2

Complete Parts 1 and 2 on Isotope HW **Make sure I have Post-Test in Bin!!

Isotopic Notation 21 Sc 46 = mass number 21 = atomic number (the total number of protons (21) and neutrons (25) 21 = atomic number (the total number of protons (21)) Sc = element symbol This atom is neutral, the number of electrons (21) is equal to the number of protons

Isotopic Notation 21 Sc-1 46 46 = mass number 21 = atomic number The total number of protons (21) and neutrons (25) 21 = atomic number The total number of protons (21) Sc = element symbol This atom is charged, the number of electrons (22) is equal to protons +1 more electron