Unit 0, Chapter 2 Flashcards

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1
Q

matter

A

anything that takes up space and has mass

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2
Q

element

A

any substance that cannot be broken down to any other substance by chemical reactions

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3
Q

compound

A

a substance consisting of two or more different elemnents combined in a fixed ratio

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4
Q

essential elements

A

a chemical element required for an organism to survive, grow, and reproduce

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5
Q

trace elements

A

an element indispensable for life but required in extremely minute amounts

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6
Q

atom

A

the smallest unit of matter than retains the properties of an element

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7
Q

neutrons

A

a subatomic particle having no electrical charge (electrically neutral), with a mass of about 1.7 x 10^-24g, found in the nucleus of an atom

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8
Q

protons

A

a subatomic particle with a single positive electrical charge, with a mass of about 1.7 x 10^-24g, found in the nucleus of an atom

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9
Q

electrons

A

a subatomic particle with a single negative electrical charge and a mass about 1/2,000 that of a neutron or proton. one or more electron move around the nucleus of an atom

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10
Q

atomic nucleus

A

an atom’s dense central core, containing protons and neutrons

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11
Q

dalton

A

a measure of mass for atoms and subatomic particles; the same as the atomic mass unit (amu)

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12
Q

atomic number

A

the number of protons in the nucleus of an atom, unique for each element and designated by a subscript

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13
Q

mass number

A

the total number of protons and neutrons in an atom’s nucleus

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14
Q

atomic mass

A

the total mass of an atom, numerically equivalent to the mass in grams of 1 mole of the atom (for an element with more than one isotope, the atomic mass is the average mass of the naturally occuring isotopes, weighted by their abundance)

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15
Q

isotope

A

one of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass

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16
Q

radioactive isotope

A

an isotope (an atomic form of a chemical element) that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy

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17
Q

half-life

A

the amount of time it takes for 50% of a sample of a radioactive isotope to decay

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18
Q

radiometric dating

A

a method for determining the absolute age of rocks and fossils, based on the half-life of radioactive isotopes

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19
Q

energy

A

the capacity to cause change, especially to do work (to move matter against an opposing force)

20
Q

potential energy

A

the energy that matter possesses as a result of its location or spatial arrangement (structure)

21
Q

electron shells

A

an energy level of electrons at a characteristic average distance from the nucleus of an atom

22
Q

valence electrons

A

an electron in the outermost electron shell

23
Q

valence shell

A

the outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom

24
Q

orbital

A

the three-dimensional (3D) space where an electron is found 90% of the time

25
Q

chemical bonds

A

an attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. the bonded atoms gain complete outer electron shells (octet)

26
Q

covalent bond

A

a type of strong chemical bond in which two atoms share one or more pairs of valence electrons

27
Q

molecule

A

two or more atoms held together by covalent bonds

28
Q

single bond

A

a single covalent bond; the sharing of a pair of valence electrons by two atoms

29
Q

double bond

A

a double covalent bond; the sharing of two pairs of valence electrons by two atoms

30
Q

valence

A

the bonding capacity of a given atom; the number of covalent bonds that an atom can form, which usually equals the number of unpaired electrons in its outermost (valence) shell

31
Q

electronegativity

A

the attraction of a given atom for the electrons of a covalent bond

32
Q

nonpolar covalent bond

A

a type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity

33
Q

polar covalent bond

A

a covalent bond between atoms that differ in electronegativity. the shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive

34
Q

ions

A

an atom or group of atoms that has gained or lost one or more electrons; thus acquiring a charge

35
Q

cation

A

a positively charged ion

36
Q

anion

A

a negatively charged ion

37
Q

ionic bond

A

a chemical bond resulting from the attraction between oppositely charged ions

38
Q

ionic compounds

A

a compound resulting from the formation of an ionic bond; also called a salt

39
Q

salts

A

another term for an ionic compound (for definiton, see card 38: ionic compound)

40
Q

hydrogen bond

A

a type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule

41
Q

van der Waals interactions

A

weak attractions between molecules or parts of molecules that result from transient local partial charges

42
Q

chemical reactions

A

the making and breaking of chemical bonds, leading to changes in the composition of matter

43
Q

reactants

A

a starting material in a chemical reaction (always on the left side)

44
Q

products

A

a material resulting from a chemical reaction (always on the right side)

45
Q

chemical equilibrium

A

in a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time