Chapter 2 The Chemical Basis Of Life

Question 0

What is an element?

Answer 0

A substance that cannot be broken down to other substances by ordinary chemical means

Question 1

What is matter

Answer 1

Anything that occupies space and has mass

Question 2

What are the 4 major chemical elements that make up living organisms

Answer 2

Oxygen (O), Hydrogen (H), Carbon (C), and Nitrogen (N)

Question 3

What are trace elements?

Answer 3

Essential elements, but only in minute quantities.

Question 4

Name the elements that account for 4% of the human body

Answer 4

Calcium, phosphorus, potassium, sulfur, sodium, chlorine, magnesium,

Question 5

Name at least 5 trace elements

Answer 5

Boron, chromium, cobalt, copper, Florine, iodine, iron, manganese, molybdenum, selenium, silicon, tin, vanadium, and Zinc

Question 6

What is a compound

Answer 6

A substance containing two or more elements in a fixed ratio

Question 7

Which are more common: compounds or pure elements?

Answer 7

Compounds

Question 8

What are the three main subatomic particles and what are their charges?

Answer 8

Proton-positive- nucleus
Neutron-no charge- nucleus
Electron-negative- electron cloud

Question 9

Atomic number is

Answer 9

Number of protons in an element

Question 10

An atoms mass number is:

Answer 10

The sum of the protons and neutrons in the nucleus

Question 11

The atomic mass is

Answer 11

The weight of the atom, approximately equal to the mass number

Question 12

What is an Isotope

Answer 12

The different isotopes of an element have the same number of protons and electrons but a different number of neutrons. Behave the same in chemical reactions

Question 13

What is a radioactive isotope and why is it radioactive?

Answer 13

An isotope in which the nucleus decays spontaneously, giving off particles and energy. Some isotopes with more neutrons are radioactive because the neutron stores excess energy that is released as radioactivity

Question 14

Why are radioactive isotopes helpful?

Answer 14

They can help us when we use them for scans like a PET or MRI because our body cannot distinguish one isotope from another so we can use them as tracers.

Question 15

How can radioactive isotopes be dangerous?

Answer 15

Radioactivity in larger quantities than given in PET’s are harmful to living organisms and potentially deadly. They damage molecules and DNA

Question 16

What are electron shells?

Answer 16

Energy levels in which electrons occur. Highest energy she’ll in living organisms has 8 electrons in the shell. Lowest has one in the first shell

Question 17

What are Chemical Bonds?

Answer 17

Attraction of two atoms to form a bond. 2 types: covalent and Ionic

Question 18

What is an Ionic bond?

Answer 18

Attractions between ions of opposite charge. One atom pulls an 1+ electrons away from a neighboring atom and they form a Ionic bond, their attraction holding them together.

Question 19

What is an Ion

Answer 19

An atom with an electric charge resulting from a gain or loss from one or more electrons

Question 20

What is the scientific definition of salt

Answer 20

A synonym for an ionic compound.

Question 21

What is a covalent bond?

Answer 21

Two atoms share one or more pairs of outer shell electrons. two or more atoms held together by a covalent bond form a molecule. Can form DOUBLE BONDS where they share two pairs of electrons

Question 22

How many covalent bonds can an atom form

Answer 22

Number that can be formed is equal to the number of additional electrons needed to fill its outer shell

Question 23

How are oxygen atoms bonded to the hydrogen atom in a water molecule?

Answer 23

Covalent bond

Question 24

What is Electronegativity?

Answer 24

An atoms attraction for its electrons, including shared electrons

Question 25

What is a polar covalent bond?

Answer 25

Produced by an unequal sharing of electrons in a covalent bond. One atom has a stronger pull making it partially negative and the other partially positive.

Question 26

Why is water a Polar Molecule

Answer 26

It has an unequal distribution of charges

Question 27

Are most of the strongest chemical bonds in organisms covalent or Ionic?

Answer 27

They are Covalent

Question 28

What is a hydrogen bond?

Answer 28

Regions of molecule are attracted to oppositely charged regions on other molecules . Positively charged region in this bond is always a hydrogen atom.

Question 29

How do hydrogen bonds make liquid water cohesive and what is the definition of Cohesion?

Answer 29

Cohesion- the tendency of molecules to stick together At trillionths a of a second hydrogen bonds are breaking and forming with molecules around them and this allows water to stick together.

Question 30

What is surface tension and how is it different from cohesion?

Answer 30

Surface tension- a measure of how easy it is to stretch or break the surface of a liquid. It is different because surface tension is a measure of the breaking point of a liquid and cohesion is what is tested.

Question 31

How are heat and temperature different?

Answer 31

Temperature measures the intensity of heat. Heat is the amount of energy associated with the movement of molecules and atoms in a body of matter.

Question 32

How does water moderate temperature

Answer 32

Water holds heat because the heat energy disrupts hydrogen bonds and is absorbed as water molecules move faster. Water cools slowly because it is releasing heat as it forms hydrogen bonds.

Question 33

Why is ice less dense than liquid water?

Answer 33

Water molecules become more stable and from bonds with four neighbors, holding them farther away. This creates a not so compact area and so the volume of water vs. an equal volume of ice is denser.

Question 34

Why is it important that ice floats?

Answer 34

Ice has to float because it insulates the water below it durning the cold months, allowing life to survive below the ice. It also has to float so oceans and lakes would not freeze completely, killing all life inside.

Question 35

What is the difference between solute and solvent?

Answer 35

The substance doing the dissolving is the solvent. The substance dissolving is the solute.

Question 36

What is an aqueous solution

Answer 36

The result when water is a solvent.

Question 37

Why are some substances more acidic?

Answer 37

They have a higher concentration of H+ ( hydrogen ions)

Question 38

Why are some substances more basic?

Answer 38

They have a higher concentration of OH- (hydroxide ions)

Question 39

Acid

Answer 39

A compound that donates hydrogen ions to a solution

Question 40

Base

Answer 40

Compound that accepts hydrogen ions and then removes them from the solution.

Question 41

What is the pH scale?

Answer 41

Describes the acidity or alkalinity of a solution. pH stands for potential of Hydrogen.

Question 42

What is a buffer?

Answer 42

Substances in organic molecules that resist change in pH by accepting H+ when it is in excess and donating H+ when it is depleted.

Question 43

Acid precipitation is:

Answer 43

Defined as rain, snow, or fog, with a pH lower than 5.6.

Question 44

What is a major concept of basic life chemistry?

Answer 44

The structure of atoms and molecules determines the way they behave.

Question 45

Chemical reaction

Answer 45

A process leading to changes in the composition of matter.

Question 46

Reactant vs products

Answer 46

Reactant: starting materials Product: the result.