chemical bonds and molecules Flashcards

1
Q

what is a molecule

A

2 or more atoms held together by chemical bonds

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2
Q

what is a compound

A

any molecule composed of 2 or more elements

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3
Q

what is a molecular formula

A

chemical symbols of the elements in the molecule with the number of each shown (C6H12O6)

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4
Q

what are covalent bonds

A

when electrons are shared to fill valance shells

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5
Q

what are the 2 types of covalent bonds

A
  1. polar covalent
  2. non-polar covalent
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6
Q

what are hydrogen bonds

A

when a hydrogen atom from one polar molecule is attracted to an electronegative atom from another molecule

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7
Q

what are ionic bonds

A

when electrons are transferred, forming ions that are attracted to each other

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8
Q

are covalent bonds strong or weak? stable or not?

A

strong and energetically stable

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9
Q

when are atoms stable (in a low energy state)

A

when their outer shell s and p electrons are full

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10
Q

what is electronegativity

A

a measure of an atoms ability to attract shared electrons towards its own positive charge

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11
Q

what do differences in electronegativity dictate

A

how electrons are distributed in covalent bonds

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12
Q

what are non-polar covalent bonds

A

when there is an equal sharing of electrons (balanced)

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13
Q

what are polar covalent bonds

A

when there is an unequal sharing of electrons (partial positive on one side, partial negative on the other). atoms of different electronegativity

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14
Q

in polar covalent bonds, what element do the atoms tend to be closer to

A

the more electronegative element

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15
Q

what are nonpolar covalent bonds

A

bonds between atoms with similar electronegativities. there is an equal sharing of electrons and no charge difference across the molecule

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16
Q

how are hydrogen bonds drawn

A

as a dotted line

17
Q

are hydrogen bonds strong or weak

A

weak electrostatic bonds

18
Q

what are hydrogen bonds made of

A

hydrogens with a partial positive charge and other atoms with a partial negative charge (typically oxygen and nitrogen)

19
Q

what connection do hydrogen bonds have to water

A
  • water molecules interact with one another via hydrogen bonds
  • hydrogens with partial positive charges are attracted to oxygens with partial negative charges
  • responsible for many of water’s important physical properties
20
Q

how are hydrogen bonds related to DNA and proteins

A

they are largely responsible for the structure of DNA and proteins as well as interactions between these macromolecules

21
Q

how are hydrogen bonds responsible for the structure of DNA and proteins

A

you can seperate DNA because hydrogen bonds are so weak

22
Q

what is an ion

A

an atom or molecule that has gained or lost one or more electrons so the net charge is not neutral

23
Q

what charge do cations have

A

a net positive charge

24
Q

what charge do anions have

A

a net negative charge

25
what is an ionic bond
when a cation binds to an anion by electrostatic (charge) attraction
26
what are the 2 types of ions
1. cations 2. anions
27
what are ionic compounds
salts
28
what is a chemical reaction
when one or more substances are changed into other substances
29
what is the equation of a chemical reaction
reactants -> products
30
many chemical reactions often require what?
a source of energy
31
in order to make chemical reactions, what energy source is often used for living organisms
an enzyme as catalyst
32
where do chemical reactions most often occur
in liquid (in life- water)
33