Chemistry Basics

Vocabulary

• Atoms: Smallest particle of an element that has all the properties of matter:

– Protons- particles in the nucleus with positive charge– Electrons- particles orbiting around nucleus with negative charge– Neutrons- particles in the nucleus with no charge

• Elements: Simplest form of a pure substance• Compounds: Two or more elements chemically combined to

form a new substance

Sub-Atomic ParticlesSub-Atomic Particles

Part of Part of AtomAtom

ChargeCharge LocationLocation Mass/SizeMass/Size

ElectronElectron - negative- negative outside outside nucleusnucleus

.0006 amu.0006 amu(too little to (too little to count)count)

ProtonProton + positive+ positive inside inside nucleusnucleus

1 amu1 amu

NeutronNeutron no chargeno charge inside inside nucleusnucleus

1 amu1 amu

Using the Periodic Table Atomic NumberAtomic Number

– Equal to # protons = # electronsEqual to # protons = # electrons– Periodic Table is arranged by this numberPeriodic Table is arranged by this number

Symbol Symbol – ““Shorthand” for the element – Note 2Shorthand” for the element – Note 2ndnd letter is letter is

always lowercasealways lowercase

Atomic Mass NumberAtomic Mass Number – Total AVERAGE mass of Protons + Neutrons + Total AVERAGE mass of Protons + Neutrons +

ElectronsElectrons

17

Cl

35.5

Electron Energy Levels• Electrons are arranged in “Shells” around nucleus in

predictable locations• Fill “seats” closest to nucleus first (concert – best seats)• “Seats” available

– Shell #1 2 electrons– Shell #2 8 electrons– Shell #3 8 electrons– Shell #4 18 electrons– Shell #5 32 electrons– Shell #6 50 electrons

• Ex. Carbon has 6 total electrons so…

Two electrons on first energy level

Four electrons on second energy level

Question: Could we fit more electrons on the second energy level if there were more electrons in carbon??

IonsIons Change in electrons which gives an atom a

charge (+ or -) You can only add or subtract electrons!

(protons don’t change)– Ex. Count the number of electrons below…

Carbon ion (-1 charge)7 electrons (-)6 protons (+)

Carbon ion (+1 charge)5 electrons (-)6 protons (+)

Neutral Carbon6 electrons (-)6 protons (+)

Types of Chemical Bonds• Ionic- Two elements bond by transferring electrons to create ions that

attract together (+ is attracted to - after an electron is transferred)

• Covalent- Two elements bond by sharing electrons (strongest bond type)

• Metallic- Two metals bond and form a “common electron cloud”. This is a cluster of shared electrons (weakest bond type)

Chemical vs. Physical Change

– Physical Change: A change that can occur without changing the identity of the substance.

– Ex. Solid, Liquid, Gas (Phase change)

– Chemical Change: Process by which a substance becomes a new and different substance

– Ex. Fire

Chemical ReactionsChemical Reactions

Chemical Reaction: a process in which the physical and chemical properties of the original substance change as new substances with different physical and chemical properties are formed

Chemical Reaction BasicsChemical Reaction Basics

H2 + O2 --> H2O

Reactants- substance that enters into a reaction

Products- substance that is produced by a chemical reaction

Reactants Products

Evidence of Chemical ChangeEvidence of Chemical Change EPOCH is an acronym that stands for evidence that a EPOCH is an acronym that stands for evidence that a

chemical reaction has occurred.chemical reaction has occurred.

– – Effervescence (bubbles and/or gives off gas)Effervescence (bubbles and/or gives off gas) – – Precipitate (solid crystals form)Precipitate (solid crystals form) – – Odor (change of smell is detected)Odor (change of smell is detected) – – Color changeColor change – – Heat (reaction either heats up or cools down)Heat (reaction either heats up or cools down)

Does sighting evidence of a chemical reaction mean that a chemical Does sighting evidence of a chemical reaction mean that a chemical reaction has undoubtedly taken place?reaction has undoubtedly taken place?

EE

PPOO

CCHH

Solution Chemistry

• Mixtures: Matter that consists of two or more substances mixed but not chemically combined

• Solutions: Homogeneous Mixture in which one substance is dissolved into another

» Solute = Substance that gets dissolved (ex. Kool-Aid powder)» Solvent = Substance that does the dissolving (ex. Water)

• Acid: Compound with a pH below 7 that tastes sour and is a proton donor.

» Ex. Citrus foods

• Base: Compound with a pH above 7 that tastes bitter and is a proton acceptor

» Ex. Cleaning Products (soap)