Earth Science Learning Plan 2 Ch. 2—Chemistry Mr. Aprill Revised: 11/19/13

The Atom An atom is the smallest particle of an element that still has all the properties of that element. 118 Known elements (As of Nov. 2011) 98 occur naturally.

Models of Structure Nucleus (+ charge) Electron Shell (- Charge) Protons (+) Neutrons (NO CHARGE) Electron Shell (- Charge) Electrons (-) In a neutral Atom p = e

Mass # & Atomic # Mass Number: protons + neutrons m = p + n Atomic Number = protons What’s the atomic number & mass number of the following elements? Ex. Iron Iron 26 Fe 55.847 Helium 2 He 4.003 Hydrogen 1 H 1.0080 Ex. Helium Ex. Hydrogen What are some ways to remember which number is the mass number and which is the atomic number?

Neutral Atoms In neutral atoms, the electrons are always equal to the protons. What is a way to remember the number of electrons? In a neutral atom, the electrons must equal the protons to have a net neutral charge. How many electrons does each have? Chlorine 17 Cl 35.453 Zinc 30 Zn 65.37 Uranium 92 U 238.03

Isotope Atoms of the same element that have different number of neutrons. What would happen if you changed the number of protons? Sulfur—32 vs. Sulfur—36 Sulfur 16 S 32.064 Argon—36 vs. Argon—38 Ar 18 39.948

Ions Electrically charged atoms Chlorine 17 Cl 35.453 Ions Electrically charged atoms What happens to the electrons in order for the atoms to become charged? gain or lose electrons Anions (Negatively charged atoms) Cations (Positively charged atoms) Sodium 11 Na 22.990 Beryllium 4 Be 9.012 Determine if a anion or cation & number of protons & electrons. Cl- Na+ Be+2 Se-2 Selenium 34 Se 78.96

Types of Chemical Bonds Ionic Charged ions with opposite charges Generally: Metals & Non-metals An IONIC BOND is the result of the transfer of one or more electrons from a metal onto a non-metal. Example: Sodium Chloride (NaCl)

Types of Bonds Covalent Bonds (Single, Double, Triple) Bonding between non-metals COVALENT BONDS involve Sharing electrons

Types of Bonds H20 (Single Covalent) O2 (Double Covalent) N2 (Triple Covalent)

Let’s see what happens when you break the bonds apart. Gummy Bear Demo What do we know? C6H12O6 (Double Covalent) 1 Serving = 17 gummy bears OR 140 calories Record observations: sound, sight, smell

States of Matter Solid: definite shape and volume. Particles are in a fixed position relative to each other. Liquid: particles are not in fixed positions. The added energy allows them to move around and change positions. Gases: particles can move freely and independently. Gases fill a container. Plasma: Most common state of matter. Stars (ie sun), magnetic field of Jupiter, Lightning bolts.

Energy From Atoms Where does energy in the U.S. come from?

Energy in the U.S. Mostly from fossil fuels (85%) Nuclear (8%) Petroleum (40%) Coal (22%) Natural Gas (23%) Nuclear (8%) Renewable Energy (7%) Hydroelectric (4%)

Compounds Compounds: contain atoms of more than one type of element that are chemically bonded together. Examples: Water (H2O), Table Salt (NaCl)

Mixtures A mixture is: composed to 2 or more substances that are NOT chemically combined. 2 Types: Heterogenous Mixture: Not mixed evenly, each component retains its own properties. Homogeneous Mixture (Solution): evenly mixed, can’t see individual components.

Chemical Properties Describes: a change that occurs when one substance reacts with another substance. Examples: Iron reacting with oxygen and water, forming iron oxide (rust). Electricity passed through water, separates water into H and O. Calcium reacting with acid and fizzing.

Physical Properties Properties that you can observe without changing a substance into a new substance. Examples: Color Density Solid, Liquid, Gas (State of Matter) Freezing/Melting Point Magnetic