UNIT 1 & 2 Review First Quarter Exam Material

Periodic Table  The Periodic Table of Elements shows all of the known elements, arranged by Increasing atomic number

The Atom  The smallest particle of an Element is an Atom  To the right are the atoms in the Element Gold

Atomic Models  Democritus Basic shapes to identify “atoms” No subatomic particles

Atomic Models  Dalton Invisible and Indivisible No subatomic particles

Atomic Models  Thomson Plum Pudding Positive substance containing negative particles

Atomic Models  Rutherford Protons in Nucleus Electrons around Nucleus

Atomic Models  Bohr Protons and Neutrons in Nucleus Electrons around Nucleus in Orbits N

Atomic Models  Electron Cloud Protons and Neutrons in Nucleus Electrons around Nucleus in a cloud formed my probability N

Subatomic Particles ParticleChargeMassLocation Proton+ 11 amunucleus Neutron01 amunucleus Electron- 10Outside the nucleus

Isotope  An Isotope is an atom with the same number of protons, but a different number of neutrons. Changing the neutrons changes the mass of the atom.

Isotope Examples  Carbon-13 and Carbon-12  The 13 and the 12 represent different masses for each atom. The “-” is a dash, not a negative sign.  13 C and 12 C are also ways to indicate different masses

Protons  Atomic number = # Protons  Carbon has 6 Protons

Electrons  Atomic number = # Electrons Unless there is a charge  Fluorine has 9 electrons  F -1 has 10 electrons  Sodium has 11 electrons  Na +1 has 10 electrons

Neutrons  Atomic mass - # protons = # neutrons  Carbon-12  (mass)12 – (protons)6 = 6 neutrons  Carbon-13  (mass)13 – (protons)6 = 7 neutrons

Drawing Bohr Models  Protons and Neutrons in nucleus  Electrons in rings outside of nucleus Ring 1 = 2 electrons Ring 2 = 8 electrons Ring 3 = 8 electrons Ring 4 = 18 electrons Ring 5 = 18 electrons Ring 6 = 32 electrons Ring 7 = 32 electrons

Chemical Formulas  Represents the number of each type of element bonded together in a compound  Remember to Multiply when there are parenthases Calcium Phosphate, Ca 3 (PO 4 ) 2 Ca-3, P-2, O-8 13 total atoms in one molecule of the compound.

Kinetic Theory  Kinetic Theory states that atoms and molecules are in constant MotionMotion

Phase Changes  Point C = Boiling from Liquid to Gas  Point B = Liquid Form  Point A = Melting from Solid to Liquid The plateau (flat part of the graph) represents the phase change. The temperature of the substance does not rise (or fall) until all of it has changed phases Time Temperature

A B C

Moles  Amedeo Avagadro came up with the “Chemist’s Dozen”  1 mole contains 6.02 x Particles

Mole Continued  The mass of one mole of any element is the same as the molar mass. Example: 1 mole of C = grams This means that 6.02 x atoms of Carbon has a mass of grams.

Sig Figs  Placeholders are NOT significant figures.  With Addition/Subtraction line up the decimals.  With Multiplication/Division the number of sig figs is based on the number that has the least number of sig figs.  Refer to the sig fig worksheet for complete rules.

Answers to sig fig problems  Determine the number of significant figures in each measurement L ________4____________ g_________4___________  Round all numbers to four significant figures. Write the answers to e-h in scientific notation kg ___847900_________ g____38.54__________  Complete the following addition and subtraction problems. Round off the answers when necessary = ______103.3_________ =_____1.2__________  Complete the following calculations. Round off the answers to the correct number of significant figures. 24 x 3.25 = _____78__________ 120 / 10 = ________10__________

Density  Density is a ratio of mass and volume. How tightly packed?  D =   Density = Mass Volume

Separating Mixtures  In the separating mixtures lab the four methods of separation were listed. Filtration Decanting Evaporation Distillation

Mixtures  A Heterogeneous mixture is one where the different parts can be easily seen. o A Homogeneous mixture is one where the particles are mixed so well that the separate parts cannot be seen.

Saturated vs Unsaturated  Saturated: Contains the maximum amount of dissolved solute for a given amount of solvent at a specific temperature and pressure. Unsaturated: Contains less dissolved solute for a given temperature and pressure than a saturated solution; has further capacity to hold more solute.

Changes  A Chemical change occurs when atoms interact and rearrange to form new substance.  A Physical change occurs when properties of the substance changes, but the identity of the substance does not change.

Making and Breaking Bonds  When a bond is broken energy is required.  When a bond is made energy is released.