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Biology I > Ch. 2 > Flashcards

Ch. 2 Flashcards

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1
Q

What is Matter?

A

Any substance in the universe that has mass and occupies space.

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2
Q

What is an Atom?

A

Extremely small particles that make up matter.

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3
Q

What are Protons?

A

A positively charged subatomic particle, found in the nucleus of an atom. Protons have a mass of 1 dalton.

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4
Q

What are Neutrons?

A

A subatomic particle found in the nucleus of an atom, has no charge. Neutrons have a mass of 1 dalton.

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5
Q

What are electrons?

A

A negatively charged subatomic particle that orbits around the nucleus of an atom. The mass of an electron is very small (about 1/2000 of a dalton), basically the mass of 0 daltons.

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6
Q

How do you measure the mass of an atom?

A

Add the number of neutrons and protons which are each worth 1 dalton.

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7
Q

What is the Atomic Number?

A

The number of protons in an atom?

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8
Q

What is the Atomic Mass?

A

The sum of the masses of the protons and neutrons in an atom?

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9
Q

What is an Element?

A

Any substance that cannot be broken down into any other substance by ordinary chemical means.

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10
Q

What is an Isotope?

A

Atoms of the same element that have different number of neutrons (Carbon-13)

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11
Q

What is a Radioactive Isotope?

A

An isotope that is unstable and tends to break up into smaller elements, this decay release lots of energy.

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12
Q

What is Half-Life?

A

The rate of decay for a radioactive substance is constant. Half-life is the amount of time needed for half of the stating material to decay.

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13
Q

Example of Half-Life

10Kg of Carbon-14 will decay into what with after a half-life of 5000 years?

A

10Kg of Carbon-14 will decay into 5Kg of Carbon-12 and 5Kg of Carbon-14 after 5000 years.

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14
Q

What is Oxidation?

A

When an atom or molecule looses an electron.

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15
Q

What is Reduction?

A

When an atom or molecule gains an electron (Gaining a negative charge).

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16
Q

What are Valence Electrons?

A

The electrons in the outermost energy level of an atom.

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17
Q

What is the Octet Rule?

A

The act of atoms wanting to completely fill the outermost energy level.

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18
Q

What is the difference between orbitals and energy levels?

A

Orbitals hold only 2 electrons. Several orbitals can be found on the same energy level.

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19
Q

What can energy levels tell us about elements with the same numbers of electrons?

A

Elements with the same number of electrons in the outermost energy levels have similar properties. This was the basis for the idea of the periodic table.

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20
Q

What does it mean for an element to be inert?

Where are they located on the periodic table?

What is the general name for these elements?

A

The outermost energy level is full.

The are located down the right side of the periodic table.

Noble Gasses.

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21
Q

What are the 5 most common elements in the human body?

A

1) Oxygen
2) Carbon
3) Hydrogen
4) Nitrogen
5) Calcium

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22
Q

What are Ions?

A

Atoms where the number of electrons does not equal the number of protons. Changing the number of electrons forms ions.

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23
Q

What is a Cation?

A

An atom with more protons than electrons, having a net positive charge.

Example: Na+

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24
Q

What is an Anion?

A

An atom with more electrons than protons, with a net negative charge.

Example: Cl-

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25
Q

What is a molecule?

A

A stable association between atoms held together by energy.

26
Q

What is a compound?

A

A molecule containing more than one type of atom.

27
Q

What is a Chemical Bond?

A

A bond between atoms resulting from attraction from oppositely charged atoms, or the sharing of one or more pairs of electrons between atoms.

28
Q

What is an Ionic Bond?

A

A bond resulting from the attraction of oppositely charged ions.

Example: NaCl (Sodium Chloride)
Sodium forms the Sodium ion Na+ by losing it’s single unpaired electron.
Chlorine needs 8 electrons to complete its outermost energy level, but only has 7. Chlorine takes the electron from Na resulting in the Chlorine ion Cl-.

29
Q

What is a Covalent Bond?

A

A bond resulting from the sharing of one or more pairs of electrons between two atoms.

Example: Two Hydrogen atoms sharing two electrons to fill the outmost energy level creating hydrogen gas (H2)

Can share more than one pair of electrons. Single, double or triple bonds based on the number of pairs of electrons being shared.

Much stronger than ionic bonds.

30
Q

What factors influence the extent of the reaction?

A

1) Temperature
- Higher temps mean molecules move faster
- The reaction rate increases with temperature
2) Concentrations of reactants and products
3) Catalysts
- A catalyst is any substance that increases the rate of a chemical reaction

31
Q

What is the chemical formula of water?

What does this mean?

A

H20

2 Hydrogen atoms are bound to an Oxygen atom. The Hydrogen atoms are arranged in a tetrahedron (pyramid) around the Oxygen atom. This leads a weakly positive electrical charge on the side with the Hydrogen atoms and weakly negative charge on the side without the Hydrogen atoms.

32
Q

What is Electronegativity?

A

A measure of the affinity for electrons. Atoms with high electronegativity “want” electrons around them, and atoms with low electronegativity don’t “want” the electrons as much.

In water, Oxygen is highly electronegative and Hydrogen has low electronegativity, causing the electrons to spend most of their time around the Oxygen atom. Gives a water molecule a weak negative and positive charge respectfully.

For this reason, water is considered a polar molecule.

33
Q

What is a polar molecule?

A

Any molecule that has an uneven charge distribution across it.

34
Q

What is a Non-Polar Molecule?

A

Any molecule that has an even charge distribution across it.

35
Q

What are the properties of water?

A

-Water clings to polar molecules
-Water stores heat
High Specific heat
High Heat of Vaporization
-Water is solvent
-Water organizes non-polar molecules
-Water ionizes

36
Q

What is Cohesion?

What is Cohesion responsible for?

A

When water molecules stick to other water molecules.

Cohesion is responsible for surface tension.

37
Q

What is Adhesion?

What is Adhesion responsible for?

A

When water molecules stick to other molecules (non-water).

Responsible for Capillary Action.
Example: Water sticking to the sides of the tube.
Trees move water up from the root system the leaves using capillary action.

38
Q

What is Specific Heat?

A

The amount of heat required to change one gram of substance one degree Celsius.

High specific heat of water absorbs the heat from chemical reactions in cells without causing increase in temp that would be lethal for cells.

39
Q

What is Heat of Vaporization?

A

The amount of heat required to change one gram of liquid to gas.

40
Q

What is evaporative cooling?

A

The evaporation of water from a surface releases lots of heat energy, which cools the surface.

41
Q

What is a hydration shell?

A

When the Oxygen end or Hydrogen end of a water molecule surround any molecule that has any polarity or is ionic.

42
Q

What is Hydrophobic Exclusion?

A

The property of water to force non-polar molecules together.

Example: Oil droplets on water surface.

43
Q

What does it mean for a substance to be Hydrophobic?

A

Water fearing; Does not mix with water; Non-polar molecules.

44
Q

What does it mean for a substance to be Hydrophilic?

A

Water loving; Mixes well with water; Polar molecules.

45
Q

What is Water Ionization?

A

The covalent bonds that hold water molecules together spontaneously break.

The process of splitting is called ionization.

46
Q

What is a Mole?

A

Weight in grams of the sum of atomic masses (Not Atomic Number).

Example: 1 Mole of Hydrogen = 1 gram.
1 mole of Iron (atomic weight of 55) = 55 grams.

47
Q

What is Molar Concentration?

A

The concentration of H+ in water.
A convenient way to express the molar concentration of H+ in a solution is pH.

pH = -log[H+]
[H+] = Concentration of H+

log scale is exponential; meaning that one change in pH value is a 10-fold change in concentration.

Example: pH = 7 means 10^-7 moles of H+
10^-7 = 0.0000001 grams of H+/liter

48
Q

What is an Acid?

A

Any substance that dissociates in water to increase the [H+]

Example: HCl

49
Q

On the pH scale, what number is considered neutral?

A

7

50
Q

What is the pH of water?

A

7

51
Q

What is a Base?

A

Any substance that combines with H+ to reduce the [H+] in water.

Example: NaOH

52
Q

What does the addition of acids (H+) do to a solution?

A

Increase the molar concentration, causing the pH to drop (Become acidic).

53
Q

On the pH scale, any number below 7 is considered basic or acidic?

A

pH lower than 7 is said to be acidic.

54
Q

On the pH scale, any number above 7 is considered basic or acidic?

A

pH higher than 7 is said to be basic.

55
Q

What is the range of the pH scale?

A

1-14; 1-7 being acidic, 7 being neutral, 7-14 being basic.

56
Q

What does the addition of a base do to a solution?

A

Bases bind up the H+ in the solution, reducing the molar concentration, causing the pH to increase (become basic).

57
Q

What is a buffer?

A

Any substance that acts as a reservoir for hydrogen ions. Buffers prevent changes in pH.

58
Q

What are the acid/base pairs in human blood to regulate pH in a reversible reaction?

A

Carbonic acid (H2CO3) and Bicarbonate (HCO3- + H+).

Keeps blood at a constant pH.

59
Q

What is the pH of blood?

A

7.4

60
Q

What will occur if the pH of blood were to change by 0.4 in either direction?

A

Blood acidosis and blood alkalosis.

61
Q

What is the reversible chemical equation for blood pH balance?

A

H20 + CO2 H2CO3 HCO3- + H+

Biology I (12 decks)

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