Review of Chemistry Created By: Mr. Kreeger

Homework and Page References Page References-Pages 29-33, Periodic Table of Elements (646-647) HW # 1-Find the amount of Protons, Neutrons and Electrons in elements 1,79,32,35 and 53 HW # 2- 1-7 on page 33 and draw the Bohr models of Mg, Na, Si, Cl and Ar. Explain which elements are the most reactive, please justify your answer. HW # 3- Draw out the model that represents HCl and CO2

Table of Contents Matter Atoms Elements Isotopes Ions Compounds Physical Property Chemical Property Atoms Atomic Structure Atomic Number Mass number Electron Energy Levels Elements Isotopes Ions Compounds Chemical Bonds Ionic Bonds Covalent Bonds Mixtures Chemical Formulas

1. Matter Anything that takes up space and has mass. Physical Property- Can be observed without changing the substance. Chemical Property- When one substance interacts with another to produce a different substance.

Introduction to Atoms

2. Atoms Smallest unit of an element that has all the properties of that element. Atomic Structure- Every atom is made of subatomic particles subatomic particles Charge Location Mass ** Electron Negative Outside nucleus 1/1840 amu (0) Proton Positive Inside nucleus 1 amu Neutron Neutral **amu- Stands for atomic mass unit, equivalent to 10^-34 Why do you think neutrons are present if they have no charge? Which element is the only one that doesn’t have neutrons?

2. Atoms Atomic Number- The amount of protons present in element. Identifies which element it is. Mass Number- The number of protons and neutrons present in an element. Can use atomic and mass number to determine the amount of protons, neutrons and electrons in an atom of an element

Activity Find the protons, electrons and neutrons for the following Argon (Atomic #=18, Mass #=39.95) Krypton (Atomic #=36, Mass #=83.80) Aluminum (Atomic #=13, Mass #=26.98) Titanium (Atomic #=22, Mass #=47.88

2. Atoms Electron Energy Levels- Inside the electron cloud there are distinct energy levels that can only hold a certain amount electrons. Determines how the element combines with other elements. (Valence Electron Shell) 1st energy level-holds 2 e- 2nd energy level-holds 8 e- 3rd energy level-holds 8 e- 4th energy level-holds 18 e-

Introduction to Elements

3. Elements A substance that can’t be broken down into simpler substances by ordinary chemical means. Over 100 elements have been discovered Only 8 elements make up 98% of the crust while 2 make up 75% (O2 and Si)-Quartz

Periodic Table of Elements

4. Isotopes Protons always remain the same however the amount of neutrons can vary. Atoms of the same element that differ from each in mass number are referred to as isotopes. Ex. Hydrogen (Protium, Deuterium,Tritium) Carbon (Carbon 14)- Used to date rocks

5. Ions The overall charge of an atom should be zero. (Protons=Electrons) When elements combine electrons sometimes are lost or gained in order to maintain stability. When e- are lost the atom has more positive charges than negative- Positive ion When e- are gained the atom has more negative charges than positive – Negative ion

6. Compounds When 2 or more elements are chemically combined. Compound has different properties than the elements that make it up. (NaCl) Molecule- Smallest complete unit of a compound

7. Chemical Bonds The way in which atoms are held together Can determine what type of bond by looking at valence energy level. Ionic Bonds- When electrons are transferred from one atom to another. Most are formed by a transfer of an e- from a metal to a non metal. Covalent Bonds- When atoms share electrons.

Activity You and a partner will look at the boohr models of NaCl (Ionic Bond) and H2O (Covalent Bond) You will explain what occurs when the elements combine and why they are considered an ionic bond and a covalent bond.

8. Mixtures 2 or more elements physically combined. Each element that makes it up retains their own properties.

9. Chemical Formulas Indicates what elements the compound contains. It also indicates the number of atoms of each element in the compound. Simple Rules An element represented by a single letter is always capitalized. (H,C,O) An element represented by two letters has first letter capitalized and second letter is lower case. (He, Fe, Si) The subscript tells the number of atoms of each element and the coefficient is always multiplied by the subscript to find total number of atoms of each element. (2(H2CO3))-4 atoms of Hydrogen, 2 atoms of Carbon, 6 atoms of Oxygen