Chapter 2

Question 1

Atoms vs. Molecules

Answer 1

Molecule: two or more atoms held together by covalent bonds; multiple atoms held together by chemical bonds(like O2)

Atoms: smallest identifiable unit of matter that still has chemical properties

Question 2

Elements vs Compounds

Answer 2

Element: all of one type of substance

Example: room full of just oxygen; even with oxygen as O2, still only one element in the room

Compound: more than one type of atom in a substance; dealing with a type of substance

Example: water being made up of two hydrogens and one oxygen
Example: carbon dioxide
Example: Ammonium

Question 3

Parts of an atom

Answer 3

(Protons and electrons of elements are meant to cancel out to have an overall neutral state)

Nucleus: Inside, it has protons and neutrons, Can vary on each element and its isotopes as well

Protons: Determine type of element(atomic number)

Electrons: Multiple ways to be shown on a diagram; Can occupy different energy levels; Ideally the same number of protons(to balance the charge!!)

Neutrons: Contribute no charge

Question 4

Atomic number and Atomic Mass/Mass Number

Answer 4

Atomic number determines element

Atomic number = number of protons

Mass number = number of protons + number of neutrons

Mass number – atomic number = number of neutrons

Question 5

Isotopes

Answer 5

“multiple versions” of an element that differ in neutron number

Affects mass number

Can undergo radioactive decay: Decay at predictable rates, Helps with dating rock stratus age

Isotopes = diff. number of neutrons

Question 6

Valence Electrons

Answer 6

Electrons in the outermost shell of the atom, called the “valence shell”; Can form chemical bonds when outermost shell is not full(?)

Valence of an atom: number of unpaired valence electrons

Full valence shell = chemically unreactive; Different atoms have different numbers of unpaired electrons

Octet Rule: a full 8 electrons, each atom must balance its need to fill the outermost shell with a need to balance charges

Question 7

Types of chemical bonds

Answer 7

Ionic and covalent

Question 8

Ionic Bonds

Answer 8

atoms EXCHANGE electrons in order to fulfill the Octet Rule

Ionic bond involves an attraction between ions of opposite charge

Question 9

Covalent Bonds

Answer 9

electrons are SHARED, STRONGEST chemical bond

Allows for satisfying the Octet Rule AND charge differentials

Name for type of covalent bond involves PAIRS of shared electrons

Question 10

Cations and Anions included under Ionic and Covalent bonds

Answer 10

Cations: loss of electron
Anions: gain of electron

Remember rule of who gains and who loses

Question 11

Nonpolar vs Polar

Answer 11

nonpolar: electrons SHARED EQUALLY; strongest bond

polar: electrons SHARED UNEQUALLY

Non polar vs polar effects how thing react/work as well

Non polar fold one way(partial charge)
Polar folds equally both ways(partial charge)

NON POLAR MOLECULES DO NOT DISSOLVE IN WATER

Question 12

Hydrogen in Bonds and interaction with water

Answer 12

Hydrogen bonds = weak (But because so many (trillions in single water droplets, can overwhelm other bonds))

Solvent: dissolves other things

Solutes are dissolved into the solvent(water in this case)

Hydrophobic: water fearing(lots of non polar, covalent bonds)

Hydrophillic: water loving(polar or ionic bonds, a charge)

oIMAGE SLIDE OF NACL Showing how charges of it react with water/hydrogen bonds in water

Hydrogen ions = hydroxide ions

Question 13

Adhesion

Answer 13

water molecules that adhere to the glass, pull upward at the perimeter

Question 14

Cohesion

Answer 14

ability of water molecules to stick to themselves

Example: spider non polar bond/lipids allow it to sit on top of the water without breaking through; Can change with heat

Water molecules at the surface from hydrogen bonds with nearby water molecules and reist the upward pull of adhesion

Question 15

Buffers

Answer 15

Buffers prevent large shifts in pH

Example: if pH of 2 given a strong base to increase pH to 10, it will increase rapidly

If solution is a buffer, will prevent rapid change until out of buffer range

Point of buffer is to keep body cells at functioning state if not an exact amount

Most biological buffers consist of a pair of molecules, one an acid and one a base

If blood gets too acidic, can create carbonic acid to bring to normal levels

Question 16

Important elements of Periodic Table for Life

Answer 16

90 naturally occuring elements, 12 important for human life

96.3% is CHON(carbon, hydrogen, oxygen, and nitrogen)

12: Carbon, Oxygen, Hydrogen, Nitrogen, Sodium, Chlorine, Calcium, Phosphorous, Potassium, sulfur, Iron, Magnesium

Sodium to sulfur considered electrolytes; Deals with protein; Iron vary small amount, but NEEDED top move cells around body

Question 17

Identify noble gases and what is special about their valence shell

Answer 17

Noble gases: full valence shell, not really reactive because of this

Helium, Neon, Argon, Krypton, Xenon, Radon, and Oganesson

Octet Rule: a full 8 electrons, each atom must balance its need to fill the outermost shell with a need to balance charges

Question 18

Which elements ionize and participate in ionic bonds?

Answer 18

Ionic: atoms EXCHANGE electrons in order to fulfill the Octet Rule

Ionic bond involves an attraction between ions of opposite charge

Solve charge imbalance by associating with each other

Occur between a metal and a nonmental

Question 19

How many valence electrons are given up/taken on?

Answer 19

It is based on the placement in the periodic table; varies in ways to be a full “noble” shell

Question 20

Which elements form covalent bonds, and how many can they form?

Answer 20

Covalent: electrons are SHARED, STRONGEST chemical bond; Allows for satisfying the Octet Rule AND charge differentials

Name for type of covalent bond involves PAIRS of shared electrons; Occur between two NON METALS; Can have single, double, and triple covalent bonds

Electrons without full valence shell do not like it so two hydrogen will bond with each other

Question 21

Valence Concepts

Answer 21

Valence electrons; Electrons in the outermost shell of the atom, called the “valence shell”; Can form chemical bonds when outermost shell is not full

Valence of an atom: number of unpaired valence electrons; Full valence shell = chemically unreactive

Different atoms have different numbers of unpaired electrons

Example: NaCL

Na has loss of electron to have cation formation(positive charge), Cl has gain of electron to have anion formation(negative charge)

Question 22

Identify acidic vs basic substances on the pH scale

Answer 22

pH scale slide, logarithmic scale, looking at exponent to identify

excess of OH = basic(lye, household bleach, household ammonia, milk of magnesia, baking soda, seawater)

excess of protons = acidic( black coffee, tomatoes, wine, vinegar, soft drinks, lemon juice, stomach acid)

water = neutral, 10^-7, 7

**NOTE: chemists do lots of rounding, biologists do not(Example: blood considered basic to biologists, considered neutral to chemists; Actual range would equal death, so different for biology)

Measures the concentration of free protons (H+) relative to hydroxyl ions (OH); Solutions that consume H+ are basic, those that generate H+ are acidic

Question 23

VIEW CONTINUM ELECTRON SHARING

Answer 23

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