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32 terms

Biology Exam I: Ch. 2

What is matter?
Anything that takes up space and has mass. Ex: Air; something that isn't matter: light (think of the filling up a balloon metaphor)
What is an element?
A substance that cannot be broken down to other substances by chemical reactions.
What is a compound?
a substance consisting of two or more different elements combined in a fixed ratio.
Difference between an element and a compound?
A compound has characteristics different from those of its elements. Table salt, for example, is sodium chloride (NaCl), a compound composed of the elements sodium (Na) and chlorine (Cl) in a 1:1 ratio. Pure sodium is a metal, and pure chlorine is a poisonous gas. When chemically combined, however, sodium and chlorine form an edible compound.
Define Subatomic particles, their charges, where they're found, and their relative mass.
Protons - positive; in nucleus; 1 dalton (or amu)
Neutrons - neutral; in nucleus; 1 dalton (or amu)
Electrons - negative; found outside nucleus; 0 nothing
What is the atomic number?
The number of protons in an atom.
What is the atomic mass?
The number of protons and neutrons in nucleus.
What are isotopes?
Different forms of the same element; they differ in number of neutrons, but they have the same # of protons and behave identically in chemical reactions
How many electrons does it take to fill the first orbital shell? The second? The third?
First shell - 2
Second shell - 8
Third shell - 8
What are valence electrons?
The electrons on the outermost orbital shell
What is a molecule?
2 or more atoms held together by covalent bonds
Difference between compound and molecule?
Compound is a mixture of at least two different elements, while a molecule is a 2 or more atoms of a single element.
What is a chemical bond?
Atoms interacting with each other to share, take, or give electrons.
What are the two strong chemical bonds?
Covalent bonds (STRONGEST) and Ionic bonds.
What are covalent bonds? Single? Double?
Two or more atoms SHARING ELECTRONS.
Single covalent bonds - sharing of one pair of valence electrons
Double - sharing of two pairs of valence electrons
What are polar covalent bonds?
The sharing of electrons UNEQUALLY; atoms have differing electronegativities
What are non-polar covalent bonds?
The sharing of electrons EQUALLY; atoms have similar electronegativities
What is electronegativity?
One atom's attraction of the electrons within one covalently bonded molecule
O > N > C > H
Oxygen - most electronegative element
What are ionic bonds?
Electron gaining or losing; e⁻ TRANSFER (NOT SHARING) between two atoms
Difference between covalent and ionic bonds?
Covalent bonds are the SHARING of electrons, whether it be equally or unequally
Ionic bonds are the GAINING or LOSING of electrons, NOT SHARING
What is an ion?
Atoms that lose or gain electrons to complete their outer shell
What's a positive ion called? A negative ion?
Positive ion = CATION
Negative ion = ANION
What is a hydrogen bond? Strong or weak?
Partial plus of a Hydrogen in a polar molecule forms a bond with a Partial Minus of another polar molecule; Weak bond.
What are our 6 Essential Elements?
CHNOPS: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur
What are trace elements?
Elements required by organisms in minute quantities; ex: humans need iodine in small quantities or we'll get goiter
Define the potential energy level of electrons and the Kinetic energy level.
Potential energy - stored energy due to location or structure; ready to use energy
Kinetic energy - energy in motion or movement; currently using
Choose 2 elements essential to life, draw the electron configuration of each as an ion and note the charge of the ion.
Ex: O - only 6 rings on outer shell, so it wants to gain 2, making it 2- charge
What is a chemical reaction? Be able to identify the products and reactants in a chemical reaction.
The making and breaking of chemical bonds.
1. Reactants - structure of chemicals prior to a chemical reaction
2. Reaction
3. Products - structure of chemicals as a result of a chemical reaction
Are Van der Waals interactions weak or strong?
What bond does a SINGLE molecule of water have? (H₂O)
Polar covalent bond.
(it's when there's more than one polar molecule that hydrogen bonding takes place)
What bond do two oxygen's share?
Non-polar covalent bond; they have equal electronegativity so they share their e⁻
Do Hydrogen Bonds only occur with water molecules?
No! Example: NH₃ (ammonia) is a hydrogen bond, the partial negative of Nitrogen bonds with the partial positive of Hydrogen.