Water, carbon and more Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is chemical evolution?

A

Chemical Evolution is the theory that simple chemical compounds in the ancient atomsphere and ocean combined via spontaneous chemical reactions to form larger, more complex substances - eventually leading to the origin of life and the start of biological evolution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What i the most common molecule found in natural gas?

A

Methane (CH4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens when a chemical reaction occurs?

A

When a chemical reaction occurs, one substance is combined with others or broken down into another substance. Atoms are rearranged in molecules; in most cases, chemical bonds are broken and new bonds form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the molecular weight?

A

The molecular weight is the sum of the mass numbers of all the atoms in the molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is molarity?

A

The number of moles of the substance present per liter of solution.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How many covalent bonds can Carbon form?

A

A carbon atom can form a total of four covalent bonds because there are four unpaired electrons in its valence shell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a primary reason for which water is vital?

A

Water is an excellent solvent - an agent that dissolves substances into a solution.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the hydrogen bond?

A

The hydrogen bond is a weak interaction between two molecules or different parts of the same molecule that results from the attraction between a hydrogen atom with a partial positive charge and another atom (usually O or N) with a partial negative charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are hydrophilic substances?

A

Hydrophilic substances are ions and polar molecules that stay in a solution because of their interactions with water’s partial charges. These attractions are said to be hydrophilic or “water loving”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are hydrophobic substances?

A

Hydrophobic substances are compounds that are uncharged and non-polar that do not interact with water through hydrogen bonding.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does water’s structure correlate with its properties?

A

Water’s small size, bent shape, highly polar covalent bonds, and overall polarity is unique among molecules. This structure causes properties such as cohesion, adhesion and surface tension.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is cohesion?

A

Binding between like molecules

Water is cohesive, which means that the water molecules cling to each other due to attractive forces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is adhesion?

A

Binding between unlike molecules

Water is adhesive because it adheres to surfaces that have any polar or charged components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an example of cohesion and adhesion in plant biology?

A

Cohesion and adhesion explain how water moves from the roots of plants to their leaves.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is another real life example of daily cohesion and adhesion?

A

A meniscus forms in a glass of water as a result of two forces:

  1. Water molecules at the surface hydrogen bond (cohesion) with the molecules below them, so they experience a net downward pool.
  2. Water molecules at the surface also adhere to the glass, allowing them to resist the downward pull. (adhesion)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What role does cohesion play in surface tension?

A

Cohesion is instrumental in surface tension, because hydrogen bonding exerts a pulling force (tension) at the surface of any body of water, the water molecules are not stable. This means they are constantly being pulled away from the surface. The body of water is most stable when the surface area is minimized.

Water resists any force that increases its surface area, making a water surface act as if it had an elastic membrane,a property called surface tension. All liquids have surface tension, but water’s is higher because of the cohesion/hydrogen bonding between molecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why is water denser as a liquid than as a solid?

A

In ice, each water molecule can form four hydrogen bonds at one time. This forms a low-density crystal structure in ice, which is has a relatively large amount of space between molecules. However, hydrogen bonds in liquid water are constantly being made and broken. The liquid therefore does not form crystal lattices and they are much more closely packed together.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is specific heat?

A

Specific heat is the amount of energy required to raise the temperature of 1 gram of a substance by 1 degree Celsius.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why does water have a high specific heat?

A

The specific heat of water is high because or the amount of energy required to break the hyrdogen bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the heat of vaporization?

A

The heat of vaporization is the energy required to change 1 gram of a substance from a liquid to a gas.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What do we know about water’s heat of vaporization?

A

The energy required is higher than that of most molecules that are liquid at room temperature, due to hydrogen bonding. As a result, water has to absorb a great deal of energy to evaporate.

22
Q

Why is water’s ability to absorb energy so critical to the theory of chemical evolution?

A

Compounds that were important in chemical evolution dissolve readily in water, they would have formed in the ocean or rained out of the atmosphere into the ocean. Once these compounds were in aqueous solution, they were well-protected from sources of energy that could break them apart. Thus, they continued to increase in concentration and react over time to continue the process of chemical evolution.

23
Q

What is disassociation?

A

it is a form of a chemical reaction within a water molecules in which H20 becomes a hydrogen ion (H+) and Hydroxide Ion (OH-). The hydrogen ion is simply a proton that associates with water molecules to form the hydronium ion (H30). This occues in in half a biliion

24
Q

What are acids?

A

Acids are substances that give up protons during chemical reactions and raise the hydrogen ion concentration of water.

25
Q

What are bases?

A

Bases are molecules or ions that acquire protons during chemical reactions and lower the hydrogen ion concentration of water

26
Q

Is water an acid or a base?

A

Water is both a weak acid and a weak base, but it (unlike most substances) can act as both an acid and a base.

27
Q

What is pH?

A

pH indicates the concentration of protons. By definition, the pH of a solution is the negative of the base-10 logarithm, or log, of the hydrogen ion concentration.
pH = -log [H+]

28
Q

What are buffers? Why are they important?

A

Buffers are compounds that minimize changes in pH, because they buffer a solution against the damaging effects of pH change. They are important to maintaining homeostasis (relatively constant conditions) in cells and tissues

Most buffers are weak acids (likely to give up a proton in a solution)

29
Q

How do chemical reactions happen?

A

Any process in which one compound or element is combined with others or is broken down; involves the making and/or breaking of chemical bonds.

Involves reactants and products

30
Q

What types of matter can be involved in a chemical reaction?

A

gases (g)
liquids (l)
solids (s)
and aqueous solutions (aq) - substances disolved in water

31
Q

What is chemical equilibrium?

A

A dynamic but stable state of a reversible chemical reaction in which the forwards and reverse reactions proceed at the same rate, so that the concentrations of reactants and products remain constant.

Can be altered by changes in temperature

32
Q

What is energy?

A

Energy is the capacity to do work or to supply heat. It exists as stored potential or as an active motion.

33
Q

What are the two major categories of energy?

A

Kinetic (constant motion) and potential energy (stored energy)

34
Q

What type of energies do molecules have?

A

Molecules have kinetic energy because they are constantly in motion. The kinetic energy of molecular motion is called thermal energy.

35
Q

What does temperature define?

A

The temperature of an object is a measure of how much thermal energy its molecules possess. If an object has a low temperature, its molecules are moving slowly. (“cold”) If an object has a high temp, its molecules are moving rapidly (“hot”)

36
Q

What is heat?

A

The transferred thermal energy between two objects with different temperatures.

37
Q

What is the first law of thermodynamics?

A

Energy cannot be created or destroyed, but only transferred or transformed

38
Q

What makes a chemical reaction spontaneous?

A

Chemical reactions are spontaneous if they proceed on their own, without any continuous external influence such as added energy.

39
Q

What two factors determine if a reaction is spontaneous or not?

A
  1. if the products have lower potential energy than the reactants
  2. if product molecules are less ordered than the reactant molecules.
40
Q

What is the second law of thermodynamics?

A

Physical and chemical processes proceed in the direction that results in lower potential energy and increased disorder.

41
Q

What is chemical energy?

A

the potential energy stored in chemical bonds

42
Q

What are organic molecules?

A

Molecules that contain carbon

Except for water, almost all molecules found in organisms contain carbon.

43
Q

Why is carbon important?

A

Carbon is the most versatile atom on Earth. It has four valence electrons, allowing it to form many covalent bonds, multiple combinations of double and triple bonds, and limitless molecular shapes.

44
Q

What is a functional group?

A

A functional group is a specific configuration of atoms commonly attached to the carbon skeleton of an organic molecule. Functional groups confer specific chemical properties to the molecules of which they are a part. Atoms typically found in functional groups include oxygen, nitrogen, sulfur, and phosphorus.

45
Q

What is the amino functional group?

A

−NH2 - It is of the amines family and acts as a base. It tends to attract a proton to form N+-H-H-H

46
Q

What is the carbonyl functional group?

A

This is in the aldehydes (COH) and ketones (>CO) family which react with certain compounds to from larger molecules

47
Q

What is the carboxyl functional group?

A

It belongs to the carboxylic acids family and acts as an acid, tending to lose a proton in a solution to form −COOH

48
Q

What is the hydroxyl functional group?

A

It is in the alcohols family (−OH). It is highly polar and makes compounds more soluble through hydrogen bonding with water. may also act as a weak acid and drop a proton

49
Q

What is a phosphate functional group?

A

−OP2 O3, belonging to organic phosphates

When several phosphate groups are linked together, breaking O-P bonds between them releases large amounts of energy.

50
Q

What is the sulfhydryl functional group?

A

−SH in the thiols family. When present in proteins it can form disulfide (S-S) bonds that contribute to protein structure