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Biology 1010 > Chapter 2 - The Chemistry of Life > Flashcards

Chapter 2 - The Chemistry of Life Flashcards

0
Q

What is matter?

A

Anything that takes up space and has mass. Matter is composed of elements.

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1
Q

What are the properties of water?

A

1) Water molecules like to “stick” together.
2) Water can moderate temperature.
3) Ice is less dense than liquid water.
4) Water is an excellent solvent.

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2
Q

What is an element?

A

A substance that cannot be broken down to other substances by chemical reactions. In other words, an element is composed of a single type of atom.

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3
Q

What is an atom?

A

The smallest unit of matter having the physical and chemical properties of an element.

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4
Q

What percentage of cells is made up of water?

A

70-95%

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5
Q

96% of living matter is made up what 4 essential elements?

A

Carbon, hydrogen, oxygen and nitrogen.

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6
Q

What is a compound?

A

Two or more elements combined in a fixed ratio.

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7
Q

What is an isotope?

A

Atoms of an element that have the same number of protons, but a different mass number.

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8
Q

Isotopes are considered stable if ______?

A

Their nuclei do not have a tendency to lose particles.

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9
Q

Are radioactive isotopes stable or unstable?

A

Unstable - nucleus decays spontaneously, giving off particles and energy.

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10
Q

What is the distance of an electron from the nucleus determined by?

A

It’s energy level

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11
Q

What is energy?

A

Capacity to cause change - ability to do work.

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12
Q

The farther an electron is away from the nucleus, the _____ potential energy it has.

A

More.

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13
Q

What is potential energy?

A

Store energy that matter possessed because of its position or location.

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14
Q

Electrons in the first shell closest to the nucleus have the _____ potential energy and electrons in the third shell have the _____ energy.

A

Lowest/most

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15
Q

An electron can move from one shell to another only if what?

A

The energy it gains or loses is exactly equal to the difference in energy between energy levels of the two shells.

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16
Q

What is electron configuration responsible for?

A

The chemical behavior of an atom. The number of electrons in the outer most shell is the most important factor in determining the chemical properties of an atom.

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17
Q

What does the chemical properties of an atom misrule depend on?

A

Number of valence electrons.

Atoms with same number of valence electrons exhibit similar chemical behavior.

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18
Q

What changes as you move left to right in a row of the periodic table?

A

Reactivity increases as you go up and right.

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19
Q

What elements are chemically unreactive?

A

Inert gases or noble gases with complete valence shells: He, Ar, Kr, Xe, Rn.

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20
Q

What elements are chemically reactive?

A

Any element with incomplete valence shells.

21
Q

What is a chemical bond?

A

Atoms staying close together held by an attraction. Completing of valence shell by sharing or transferring valence electrons.

22
Q

What is the strongest kind of chemical bond?

A

Covalent and ionic bonds.

23
Q

Lewis dot structures: A metal or non-metal is considered a ____?

A

Ionic compound (charger atoms)

24
Q

Lewis for structures: metals ______ electrons and become ________.
Non metals become ______.

A

Give up
Positive
Negative

25
Q

What determines an atoms bonding capacity?

A

The number of electrons in an atoms outer shell.

26
Q

What is an atoms bonding capacity referred to?

A

Valence - usually equals the number of unpaired electrons required to complete the atoms valence shell.

27
Q

What is a molecule?

A

Two or more atoms held together by a covalent bond.

28
Q

What is a covalent bond?

A

Two atoms sharing a pair of electrons.

29
Q

What is electronegativity?

A

The attraction of a particular atom for the electron of a covalent bond. Affects the strength of bonds.

30
Q

The more electronegative an atom is, the _______ it pulls shared electrons toward itself.

A

More strongly.

31
Q

What is a non polar covalent bond?

A

Atoms have an equal attraction for the shared electrons. Ex h2, o2.

32
Q

What is a polar covalent bond?

A

Electrons are not shared equally.

Ex. Methane ch4 carbon slightly more electronegative than hydrogen.

33
Q

What is the most electronegative elements found in nature?

A

Oxygen.

34
Q

The unequal sharing of electrons results in O atom having a slight negative charge and H atom having a slight positive charge. (Electrons spend more time around oxygen) what does this result in?

A

Dipole.

35
Q

What is an ionic bond?

A

Opposites attract. Involves electron transfer, when atoms are so unequal in their attraction for valence electrons that the more electronegative atom strips an electron away from parter. Each atom ends up with complete valence shells.

36
Q

What does the transfer of an electron (in ionic bonds) result in?

A

Charge of -1

37
Q

What is a cation and anion?

A

Positive charge/negative charge

38
Q

What can affect the strength of ionic bonds in nature?

A

The strength of ionic bonds are affected by the environment, ex the presence of water.

39
Q

Generally speaking, in water, covalent bonds are ______ than ionic bonds.

A

Stronger.

40
Q

What are 3 types of weak bonds?

A

1) ionic bonds are weak in aqueous solutions or water.
2) hydrogen bond
3) van der waals interactions

41
Q

When is a hydrogen bond formed?

A

When a hydrogen atom is covalently bonded to a more electronegative atom, a dipole forms between these two atoms. Partial + charge attracted to partial - charge.

42
Q

In living cells, what are the two electronegative partners of hydrogen?

A

Oxygen and nitrogen.

43
Q

What are van der waals interactions?

A

The constant motion of electrons means that even molecules with non polar covalent bonds may have + and - charged regions.
These very weak interactions only occur when molecules are very close to each other.

44
Q

What determines the size and shape of a molecule?

A

Positions of the atoms orbitals.

45
Q

Would methane dissolve well in water?

A

No because it is non polar. Strongly polar molecules tend to dissolve easily in water.

46
Q

What is a molecules biological function related to?

A

It’s shape. Molecule shape is due to hybrid orbitals.

47
Q

What is a chemical reaction?

A

Making and breaking of chemical bonds leads to changes in composition of matter.

48
Q

What is chemical equilibrium?

A

Point at which reactions offset one another. Forward rate of a reaction equals the rate of the reverse reaction.
Ex. When ammonia decomposes as rapidly as it forms.

49
Q

What is one of the factors affecting the rate of a reaction?

A

Concentration of reactants. Greater concentration=more frequently they collide.

Biology 1010 (5 decks)

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