Biology: Chapter 2: The Chemical Context Of Life

Front 1

matter

Back 1

anything that takes up space and has mass.

Front 2

elements

Back 2

substances that cannot be chemically broken down to other types of matter.

Front 3

compound

Back 3

made up of two or more elements combined in a fixed ratio.

Front 4

96% Elements of Life

Back 4

Carbon, Oxygen, Hydrogen, and Nitrogen.

Front 5

trace elements

Back 5

like Iron (Fe) and Iodine (I) may be required in very minute quantities.

Front 6

The remaining 4% of The Elements of Life

Back 6

Calcium (Ca), Phosforus (P), Potassium (K) , Sulfur (S), Sodium (Na), Chlorine (Cl), and Magnesium (Mg)

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atom

Back 7

the smallest unit of matter retaining the properties of a particular element.

Front 8

neutrons

Back 8

uncharged subatomic particles found in the nucleus.

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protons

Back 9

positively charged subatomic particles packed tightly together to form the atomic nucleus.

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electrons

Back 10

negatively charged subatomic particles that form a cloud around the atomic nucleus.

Front 11

a dalton

Back 11

is the measurement unit for atomic mass. Protons and neutrons have a similar mass of about 1.7 x 10^-24 grams or close to one dalton each. Electrons have negligible mass.

Front 12

atomic number

Back 12

characteristic to each element, is the number of protons in the nucleus of each of its atoms.

Front 13

mass number

Back 13

equal to the number of protons and neutrons in the nucleus and approximates the mass of an atom of that element in daltons.

Front 14

atomic mass

Back 14

the total mass of an atom.

Front 15

isotopes

Back 15

number of neutrons vary among the atoms of an element, with the number of protons constant. slightly different masses but the same chemical behavior.

Front 16

radioactive isotopes

Back 16

unstable isotopes. spontaneously decaying, giving off particles and energy. important tools in research and medicine. too much exposure poses a significant health hazard.

Front 17

energy

Back 17

the capacity to cause change.

Front 18

potential energy

Back 18

energy stored in matter as a consequence of its positon or structure.

Front 19

electron shells

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electrons can be located in different shells surrounding the nucleus and increase in potential energy as their distance from the positively charged nucleus increases.

Front 20

valence electrons

Back 20

electrons in its outermost electron shell that dictates the chemical behavior of an atom by their distribution.

Front 21

valence shell

Back 21

outermost electron shell

Front 22

orbital

Back 22

is the three dimensional space or volume within which an electron is most likely to be found. No more than two electrons can occupy the same orbital.

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chemical bonds

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hold atoms together that have incomplete valence shells by either sharing or transferring electrons such that each atom is able to complete its valence shell.

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covalent bond

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when two atoms share a pair of valence electrons.

Front 25

molecule

Back 25

consists of two or more atoms held together by covalent bonds.

Front 26

structural formula

Back 26

indicates both the atoms and bonds in a molecule.

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a molecular formula

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indicates only the kinds and numbers of atoms.

Front 28

The _________ or bonding capacity of an atom usually equals the number of unpaired electrons in its valence shell.

Back 28

valence

Front 29

What are the valences of the four most common elements of living matter?

Back 29

h

Front 30

electronegativity

Back 30

the attraction of a particular atom for shared electrons.

Front 31

If the atoms in a molecule have similar electronegativities, the electrons remain ______________ and the bond is said to be a _________________.

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equally shared and nonpolar covalent bond.

Front 32

If one is more electronegative, it does what and forms what

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pulls the shared electrons closer to itself creating a polar covalent bond.

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ions

Back 33

charged atoms

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ionic bonds

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if two atoms are very different in their attraction for valence electrons, the more electronegative atom may completely transfer an electron from the other atom, resulting in the formation of charged atoms.

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cation

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ion that lost the electron is positively charged.

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anion

Back 36

atom that gained the electron.

Front 37

ionic bond

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may hold these ions together because of their opposing charges.

Front 38

ionic compounds

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salts, often exists as three dimensional crystalline lattice arrangements held together by electrical attractions.

Front 39

hydrogen bonds

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hydrogen bond that is covalently bonded to an electronegative atom has a partial positive charge and can be attracted to another nearby electronegative atom.

Front 40

van der Waals interactions

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all atoms and molecules are attracted to each other when in close contact by these. Momentary uneven electron distributions produce changing positive and negative regions that create these weak attractions.

Front 41

chemical reactions

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involve the making or breaking of chemical bonds.

Front 42

chemical equilibrium

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reached when the forward and reverse reactions proceed at the same rate, and the relative concentrations no longer change.

Front 43

Word Roots: an-

Back 43

not (anion: negatively charged ion)

Front 44

Word Root: co-

Back 44

together

Front 45

Word Root: -valent

Back 45

strength (covalent bond: a strong bond between atoms that share one or more pairs of valence electrons)

Front 46

Word Root: electro-

Back 46

electricity (electronegativity: the attraction of a given atom for the electrons of a covalent bond)

Front 47

Word Root: iso-

Back 47

equal (isotope: one of several forms of an element, each with same number of protons but a different number of neutrons)

Front 48

Word Root: neutr-

Back 48

neither