Atomic Structure 3 Parts of the Atom Subatomic

Atomic Structure

3 Parts of the Atom: Subatomic Particle Proton Relative Mass Charge Where Found 1 +1 In Nucleus Neutron 1 0(neutral) In Nucleus Electron 0 -1 Outside nucleus in electron cloud

Key Points: • The nucleus of an atom contains roughly 99. 9% of the mass of an atom. • More than 99. 9% (that's a popular number) of the atom is "empty space" occupied by moving electrons (which weigh very little). If you could make an atom as big as a football stadium, then its nucleus would still be as small as a marble. • We cannot predict the exact location—only a probable location—of an electron at any given time. • Electrons in the outer energy levels(called valence electrons) are involved with forming compounds.

What is the relative mass of a proton? A. O B. 1 C. 2 D. 3

What is the charge of an electron? A. Positive B. Negative C. Neutral

What subatomic particle has a relative mass of 1 and a (+) charge A. Electron B. Proton C. Neutron

What subatomic particle(s) are found inside the nucleus? A. Electron B. Proton C. Neutron D. Protons and Neutrons E. Protons and Electrons

Each energy level can hold a specific # of electrons:

How many electrons are found in the 3 rd energy level? A. B. C. D. E. 0 2 8 10 18

How do we know so much about the atom? Who discovered the atom? How long ago? It started along time ago with a guy named Democritus and went through several changes until a couple of dudes named de Broglie and Schrodinger I hope we get a handout with all these names!!

I look pretty good for a dude 2400 years old!!! In Greek, the prefix "a" means "not" and the word "tomos" means cut. Our word atom therefore comes from atomos, a Greek word meaning uncuttable.

John Dalton: early 1800’s

JJ Thomson--1897 Plum Pudding Model But the atom is Neutral!!!! While studying electric discharge in Cathode-ray tubes, Thomson discovered the electron!!!

Ernest Rutherford--1908 Rutherford’s Gold Foil Experiment In an attempt to build on Thomson’s model, I discovered some amazing stuff!!! What Rutherford Expected Actual Results Rutherford’s Model

Notice 2 things: 1. Atom is made up of mostly empty space. 2. Electrons are scattered randomly! Rutherford’s Atomic Model

Nucleus Electrons Neils Bohr--1913

Bohr Model of the Atom The Bohr Model has the following features: 1. There is a nucleus(Rutherford’s Discovery) 2. The electrons move about the nucleus in “stationary, stable states”(later referred to as orbits)!

The Wave Model of the Atom

Discovery of the neutron James Chadwick--1932 In 1932, Sir James Chadwick, working to interpret the results of other scientists, discovered the neutron!!!

Which scientist is credited with the discovery of the electron? A. Dalton B. Thomson C. Rutherford D. Bohr

Which scientist is credited with the discovery of the “orbital” motion of the electrons around the nucleus? A. Dalton B. Thomson C. Rutherford D. Bohr

Which scientist is credited with the discovery of the nucleus? A. Dalton B. Thomson C. Rutherford D. Bohr

Which scientist is credited with the 1 st Atomic Theory? A. Dalton B. Thomson C. Rutherford D. Bohr

I’m going to find Mr. Rodgers Mrs. Hardeman Mrs. Wolcott Mrs. Elliot Let’s wrap this up!!! That’s a bunch of stuff!!! Mrs. Hatfield

Democritus/Dalton

Chemical Symbols • Shorthand method of writing the names of the elements on the period table. – All symbols either have 1 or 2 letters. • If one letter, then that letter is capitalized. • If two letters, then first letter is capitalized, second letter is lowercase. • H—Hydrogen • Cu—Copper • Cl—Chlorine C-Carbon Mg—Magnesium K-Potassium

Classwork • P. 511 #1 -5