Unit 1: Chemistry of Life

Question 1

What is the metric system conversion stairs? How do you convert between them?

Answer 1

Remember: King Henry Died Unexpectedly Drinking Chocolate Milk
1. Kilo-1000
2. Hecto-100
3. Deca- 10
4. Meter/Liter/Gram- 1
5. Deci- 0.1
6. Centi- 0.01
7 Milli- 0.001
To convert between them:
As you go up the steps, (milli to kilo), you divide by 10. As you go down the steps (kilo to milli), you multiply by 10.

Question 2

Convert 10 mm to km.

Answer 2

10mm = 0.00001km

Question 3

What are the four factors of significant figures?

Answer 3

N- Non-zero numbers are always significant.
E- Embedded zeros are always significant.
Ex. 2003- 4 significant figs
L- Leading zeros are never significant.
Ex. 0.001- One significant fig
T-Trailing zeros are significant only if they contain a decimal place.
Ex. 2.30- 3 significant figs
200- One significant fig

Question 4

Calculate the significant figure of the following calculation.
3.54 x 2.6458 x 7.48764

Answer 4

Full answer should be 70.130224 but final answer according to significant figures should be 70.1

Question 5

Calculate the significant figure of the following calculation.
38.65 x 105.93

Answer 5

Reduce to 4 sig figs 4,094

Question 6

Calculate the significant figure of the following calculation.
22.903m x 0.0092m x 16.9753m =

Answer 6

3.6m^3

Question 7

What is a fact?

Answer 7

A fact is an observation so firmly supported by evidence that we assume it’s true, and act as if it were true. (There is no certainty in science).

Question 8

What is a hypothesis?

Answer 8

A casual explanation of an observation/fact that has not been sufficiently tested.

Question 9

What is a scientific theory?

Answer 9

A well-substantiated explanation of some aspect of the natural world, based on a body of facts and laws that have been repeatedly confirmed through observation and experiement.

Question 10

What is scientific law?

Answer 10

Describes a natural phenomenon

Question 11

What is the valence shell?

Answer 11

The outermost shell of an atom with e^- is called the valence shell.

Question 12

What is valence?

Answer 12

The number of unpaired electrons in the outermost shell is called its valence.

Question 13

When are atoms the most stable? Give an example.

Answer 13

Atoms are most stable when the valence shell is full.
Ex. Hydrogen atoms each have one unpaired electron in their electron shells. An H2 molecule has two shared electrons through a covalent bond

Question 14

What are the four factors of a covalent bond?

Answer 14

S- Protons and neutrons are shared by two atoms to fill their orbitals.
T- Outer-shell electrons are transferred to fill the inner electron shell of another atom.
O- Electrons from the same atom, but
opposite spins, are paired.
R- Electrons are removed from one atom and transferred to another becoming oppositely charged.

Question 15

Covalent bonds can be _____ or ______.

Answer 15

Covalent bonds can be polar or nonpolar.

Question 16

What is electronegativity? What are examples?

Answer 16

A measure of how strongly an atom pulls shared electrons toward itself in a bond.
Examples: Oxygen, which has eight protons and only two electron shells, is among the most electronegative of all elements. Nitrogen, which has one fewer proton, has a somewhat lower electronegativity than oxygen.
Sulfur, carbon, hydrogen, and phosphorus have low and approximately equal electronegativities.

Question 17

What is a polar covalent bond? What’s an example?

Answer 17

A covalent bond in which electrons are shared unequally between atoms differing in electronegativity. Results in the more electronegative atom having a partial negative charge and the other atom having a partial positive charge.
Example: Both bonds in a water molecule between the hydrogen and oxygen atoms are polar covalent bonds. The partial charges on water molecules—due simply to the difference in electronegativity between oxygen and hydrogen—are one of the primary reasons that life exists. Ammonia (NH3) is a polar covalent bond.

Question 18

What is a nonpolar covalent bond? What’s an example?

Answer 18

A covalent bond in which electrons are equally shared between two atoms of The same or similar electronegativity.
Example: Because carbon and hydrogen have approximately equal electronegativity, the electrons in a C-H methane bond are shared equally or symmetrically (nonpolar covalent bond). Hydrogen is another example.

Question 19

What are ionic bonds? Examples?

Answer 19

A chemical bond formed when an electron is completely transferred from one atom to another. This results in ions remaining associated due to their opposite electric charges.
Example: Table salt (Sodium Chloride) (NaCI) is a crypt composed of two ions. CI- and Ha+

Question 20

What results when electrons aren’t shared equally?

Answer 20

Charges result when electrons are not shared equally.

Question 21

What are single bonds? Three examples?

Answer 21

A single bond is formed when two atoms share one pair (2 electrons) of electrons.
Examples: Water (H2O), Ammonia (NH3), and Methane (CH4)

Question 22

What are double bonds? Examples?

Answer 22

A double bond is formed when two atoms share two pairs (4 electrons).
Example: Carbon Dioxide (CO2)

Question 23

What is a triple bond?

Answer 23

A triple bond is formed when two atoms share three pairs (6 electrons).
Example: Molecular nitrogen (N2)

Question 24

How is water polar? What bond forms between water molecules?

Answer 24

The electrons from the hydrogens are pulled toward oxygen. Hydrogen bonds form between water molecules.

Question 25

What are hydrogen bonds? Examples?

Answer 25

A weak interaction between two molecules resulting from the attraction between a hydrogen atom with a partial positive charge and another atom with a partial negative charge. Example: When two water molecules approach each other, the partial positive charge on hydrogen attracts the partial negative charge on oxygen. This weak electrical interaction is an example of a hydrogen bond. HF (hydrogen Fluorine), and NH3 (Ammonia) are other examples.

Question 26

What are two examples of a molecules that dissolves in water? What type of compound is it?

Answer 26

Glucose (C6H12O6) a polar compound and table salt (NaCI) an ionic compound dissolves in water

Question 27

What type of molecular compound doesn't dissolve in water?

Answer 27

Nonpolar molecules don't dissolve in water.

Question 28

What is hydrophilic? What type of bond are they usually?

Answer 28

Interacting readily with water. Hydrophilic compounds are typically polar compounds containing partially or fully charged atoms.

Question 29

What is hydrophobic? What type of bond are they?

Answer 29

Not interacting readily with water. Hydrophobic compounds are typically nonpolar molecules.

Question 30

A ______ forms where water meets a _______, as a result of two ____.

Answer 30

A meniscus forms where water meets a solid surface, as a result of two forces.

Question 31

What is adhesion?

Answer 31

Water molecules that adhere to the glass and pull upward at the perimeter.

Question 32

What is cohesion?

Answer 32

Water molecules at the surface form hydrogen bonds with nearby water molecules and resist the upward pull of adhesion.

Question 33

Water has high ________.

Answer 33

Water has high surface tension.

Question 34

What is surface tension?

Answer 34

The cohesive force that causes molecules at the surface of a liquid to stick together, resisting deformation of the liquid’s surface.

Question 35

How does surface tension relate to water?

Answer 35

Because of surface tension, light objects do not fall through the water's surface.

Question 36

______ is less _____ than _____.

Answer 36

Solid water (ice) is less dense than liquid water.

Question 37

Why is solid water less dense than liquid water? (3 ideas)

Answer 37

1. In ice, water molecules form a crystal lattice. 2. In liquid water, no crystal lattices form. 3. Liquid water is denser than ice. As a result, ice floats.

Question 38

What are antacids? What does that have to do with pH?

Answer 38

Antacids are substances that help neutralize stomach acid. They are usually basic (alkaline) compounds. Antacids help raises the pH of the stomach by neutralizing the hydrochloric acid (HCl). Makes environment less acidic (less heartburn, indigestion).

Question 39

How can you calculate a pH or H+ concentration?

Answer 39

pH = -log[H+]

Question 40

What is acidic?

Answer 40

Solutions that contain acids have a proton concentration pH < 7 because acidic molecules tend to give up protons. Acids give up protons and raise [H3O+], which decreases pH.

Question 41

What is basic?

Answer 41

Solutions that contain bases have a proton concentration pH > 7 because basic acquire protons when they react with water, which increases pH.

Question 42

What are the three steps to atmospheric evolution on Earth?

Answer 42

1. Early Earth's atmosphere was made of simple gases like methane, ammonia, and water vapor. 2. Energy from things like lightning helped turn these gases into simple organic molecules (amino acids/nucleotides). 3. These molecules then combined to form complex molecules like proteins, RNA, and DNA, which are the building blocks of life.

Question 43

What was the significance of Stanley Miller's experiment?

Answer 43

1. Miller simulated conditions of early Earth's atmosphere by mixing water (H₂O), methane (CH₄), ammonia (NH₃), and hydrogen (H₂) in a sealed flask, and then subjected the mixture to electric sparks to simulate lightning. 2. When Miller analyzed samples, he found large quantities of hydrogen cyanide and formaldehyde. 3. It showed that life’s basic molecules could form without the need for life to already exist.

Question 44

What is an atom? What is its structure?

Answer 44

Has a positively charged nucleus surrounded by negatively charged electrons.

Question 45

What is an ion? What's two examples?

Answer 45

An atom or a molecule that has lost or gained electrons and thus carries a full electronic charge, either positive (cation) or negative (anion). Example: The sodium ion is written NA+ and, like other positively charged ions, is called a cation. Chlorine atoms (Cl), in contrast, tend to gain an electron, filling their outermost shell.

Question 46

What is a molecule?

Answer 46

When multiple atoms combine together, this creates a molecule.

Question 47

What is responsible for electronegativity?

Answer 47

It’s a combination of two things—the number of protons in the nucleus and the distance between the nucleus and the valence shell.

Question 48

What are ionic bonds similar in principle to?

Answer 48

Are similar in principle to covalent bonds, but instead of being shared between two atoms, the electrons in ionic bonds are completely transferred from one atom to the other.

Question 49

Why do ionic bonds occur?

Answer 49

The electron transfer occurs because it gives each of the two resulting atoms a full valence shell.

Question 50

What is pH?

Answer 50

A measure of the concentration of protons in a solution and thus of how acidic or basic the solution is.

Question 51

Why are hydrogen bonds important in biology?

Answer 51

Because of their role in dissolving substances in an aqueous solution.

Question 52

What are bonds?

Answer 52

Single, double, and triple bonds refer to the number of electron pairs shared between two atoms in a covalent bond.

Question 53

What is the difference between covalent bonds and ionic bonds?

Answer 53

Covalent bonds share electrons while ionic bonds gain or lose electrons to achieve a full valence shell.

Question 54

What is chemical evolution?

Answer 54

Simple chemical compounds in the early atmosphere and ocean combined via chemical reactions to form larger, more complex substances, leading to the origin of life.

Question 55

What are the five properties of water?

Answer 55

1. Surface Tension (see flashcard) 2. High specific heat capacity- water absorbs and retains heat (a lot of energy needed to change its temp). 3. High heat of vaporization- Takes a lot of energy to convert water from liquid to gas. 4. Universal solvent- water dissolves many substances due to its polarity 5. Density (see flashcards) (SHHUD)