CHEMISTRY REVIEW

Chapters 1 & 2

Atoms and Elements and Chemical Reactions (Period 5)

T = CHAPTER 1 ATOMS AND ELEMENTS

Elements and Atoms

Matter - anything that takes up and has mass

Elements – A substance that cannot be broken down

into any other substance

Compound – a substance made of two or more

elements that is combined chemically in a specific

ratio.

Mixture – when two or more substances are

combined-non chemically (dirt, air, mulch, fish in

water, mud)

Atom – the smallest particle of an element

T = CHAPTER 1 ATOMS AND ELEMENTS

Atomic Theories

Daltons - composed that atoms can not divided, they are all alike, every compound is made of atoms in specific ratios, atoms can not be created or destroyed.

Thomson – chocolate chip cookie model (electrons are everywhere)

Rutherford - Gold foil experiment (the existence of a nucleus)

Bohr – onion – orbitals (looks like the planets orbiting the sun which would be the nucleus and planets are the electrons in the orbits

Cloud – electrons can be anywhere

Modern (Chadwick) - neutrons

Elements and Periodic Table Period –horizontal

Group (family) – column- vertical

Metals – most of the chart until Group 13

Non Metals – Groups 14-18

Semi Metals – Staircase 13-17

Atomic Number – number in the box= # protons if neutral = # of electrons

Symbols – the shortened version of an element ex. Oxygen = O, Lithium = Li, Sodium = Na, Sulfur = S

Valence Electron – Electrons on on the outer orbital. They have the highest energy level. Gr. 1 and 2 like to give up electrons because losing 1 or 2 electrons is the easiest way to be KING(noble gases). Halogens like to take electrons to gain noble status.

T = CHAPTER 1 ATOMS AND ELEMENTS

T = CHAPTER 1 ATOMS AND ELEMENTS

Elements and Periodic Table Metals - luster, malleable, ductile, conducts heat,

conductive, sea of electrons

Semi Metals – can exist as both a metal or a non metal depending on temperature, what it is paired with!

Non Metals - all non metals have at least four valence electrons and Halogens become stable when they gain or share electrons

Electron Dot Structure – shows the number of valence electron as dots around the symbol

Atomic Orbital Structure - p/n in middle, layer like an onion or planets, circles. First orbit has 2, all others filled up to 8. The outermost circle holds the valence electrons

T = CHAPTER 1 ATOMS AND ELEMENTS

Group Names Alkali Metals – Group 1

Alkaline and Earth – Group 2

Halogens – Group 17

Nobel Gases – Group 18

Covalent Bonding – Share electrons

Usually Form between non metals

Become more stable when they share

Non Polar – Electrons shared equally

Polar – Electrons shared unequally

Single Bonds – 2 electrons

Double Bonds 4 electrons

Triple Bonds 6 electrons

Do not conduct electricity

T = CHAPTER 1 ATOMS AND ELEMENTS Ionic Bonding

Transfer of electrons

Always polar

Bond is due to the attraction of the opposite charges

Form crystals

High melting points

Conduct electricity

Metallic Bonding – Attraction between a positive metal ion and the electrons

surrounding it

Consists of a positively charged metal ion embedded in a sea of electrons

Alloy – material made of two or more elements that have the characteristics of a metal

Every metal ion is held by a metallic bond

Conduct Heat and Electricity

Lust and Malleability and ductility

CHAPTER 2 OBSERVING CHEMICAL REACTIONS

T= Observing Chemical Change

Properties and Changes of Matter

Physical Properties –

Observable change without changing the substance

Ex squishing, vaporization, Change of state,

Chemical Properties

Observable change which DOES change the substance into another substance

Ex. Fire(burning), oxidized, rusted, tarnish

Physical Change

A change in its state but the substance is not changed

Chemical Change

Changing the substance into another substance

T= OBSERVING CHEMICAL CHANGE

Evidence for Chemical Reactions

Sensing a change in smell

See a precipitate

Solid formed from two liquids

Change of heat/temperature

Exothermic – release of heat (feels hot)

Endothermic – absorbing heat (feels cold)

Change of color

T= DESCRIBING CHEMICAL CHANGE

Chemical Equation Reactant + reactant YIELDS Product + Product

Short easy way to show a chemical reaction using symbols

Yield = arrow

Product is the end solution/material/substrate

Reactants are the substances in the beginning

Coefficient is the number in front which represents the number of molecules of that particular substance

Conservation of Mass The principal stating that matter is not created nor

destroyed during a chemical reaction Closed System – Where substances can not come in or be let out!

Balloon, air bag(partial), class jar with lid, zip lock bag, sealed box,

Open System – System in which matter can enter and or escape Beaker (open), campfire, cooking pot

T= DESCRIBING CHEMICAL CHANGE

Balancing Chemical Equations

Both sides have the same number of each type of

atom.

Write the equation

Count the atoms (on each side)

Use coefficients to balance the atoms

Look Back and Check

T= CLASSIFYING CHEMICAL REACTIONS

Replacement - Switch Partners

Synthesis – Simple to Complex

Decomposition - Complex to

Simple

T= CONTROLLING CHEMICAL REACTIONS

Temperature

Surface Area – Simple to Complex

Concentration - Complex to Simple

Inhibitor - Slows down a reaction

Catalyst – Speeds up a reaction

T= CONTROLLING CHEMICAL REACTIONS

Temperature - adds or removes energy – increased temp increases the reaction rate.

Surface Area – greater surface area increases the reaction

Concentration – higher concentration usually increases the reaction rate

Inhibitor - Slows down a reaction

Catalyst – Speeds up a reaction

T= FIRE AND FIRE SAFETY

Temperature - adds or removes energy – increased temp increases the reaction rate.

Surface Area – greater surface area increases the reaction

Concentration – higher concentration usually increases the reaction rate

Inhibitor - Slows down a reaction

Catalyst – Speeds up a reaction