Biology Ch. 2 Concepts
Terms
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- electrons located in _______
- orbitals
- electrons are maintained in their orbits because
- they are attracted to the oppositely charged nucleus (protons)
- Atomic Energy Levels
-
When an electron absorbs energy, it moves to higher energy levels, farther from the nucleus. When an electron releases energy, it falls to lower energy levels, closer to the nucleus.
Energy Level (#/letter)
En. Released> Energy Absorbed>
(3M) (2L) (1K) N (1K) (2L) (3M) - Who created the Periodic Table?
- Dmitri Mendeleev
-
Inert (Noble) Gases
What are they
Names -
atoms with full outer energy levels
nonreactive
8 electrons in outer level (except 2 for He)
HeNeArKrXeRn - Octet Rule
- atoms tend to establish a full set (8) of valence electrons
-
4 elements that make up 96% of your body weight.
How much of each (%)? -
1. Oxygen 65%
2. Calcium 18.5%
3. Hydrogen 9.5%
4. Nitrogen 3.3%
OC in 65 and 18.5
HN in 9.5 and 3.3 -
Ionic bonds
1) When does this form?
2) What types (groups of atoms)?
3) Explain about the bond -
1) When oppositely charged ions attract
2) metal and nonmetal (L and R)
3)bonds are not formed b/t particular ions in the compound; rather, they exist b/t an ion and all of the oppositely charged ions in its immediate vicinity. -
Covalent Bonds
1) When does this bond form?
2) What types of groups? -
1) when 2 atoms share 1 or more pairs of valence electrons
2) Those that both need to gain electrons, nonmetals, on R side - 3 Factors Influencing the Extent to which Chemical Reactions Occur
-
1) Temperature
2) Concentration of reactants and products
3) Catalysts - Water structure
- Oxygen atom bound to 2 H atoms by covalent bonds
- "the most outstanding chemical property of water"
-
ability to form weak chemical associations w/ only 5 to 10% of the strength of covalent bonds.
Hydrogen Bonding -
1) ionization- define
2) What two ions is it afterwards? -
1)when covalent bonds in water spontaneously break
2) hydrogen and hydroxide ions - pH
-
negative logarithm of the H+ ion concentration in a solution
pH= -log [H+]
acids less than 7, more hydrogen ions. - key buffers in humans
- carbonic acid, bicarbonate