Chapter 2: The Chemical Context of Life

Question 1

Matter

Answer 1

anything that takes up space and has mass

Question 2

Element

Answer 2

substance that cannot be broken down to other substances by chemical reactions

Question 3

Compound

Answer 3

substance consisting of 2+ different elements combined in a fixed ratio

Question 4

Essential Elements

Answer 4

elements that an organism needs to live a healthy life and reproduce

Question 5

Trace Elements

Answer 5

required by organisms in minute quantities

Question 6

Atom

Answer 6

smallest unit of matter (that still retains properties of an element)

Question 7

Atomic Nucleus

Answer 7

Center of an atom, packed with protons and neutrons

Question 8

Isotopes

Answer 8

Same element, same # of protons, different # of neutrons (therefore greater mass)

Question 9

Atomic Number

Answer 9

Not Important for test

• Number of protons in an atom
• specific to each element

Question 10

Radioactive Isotopes

Answer 10

Isotope where the nucleus SPONTANEOUSLY decays… giving off particles and energy

Question 11

Radioactive Tracers

Answer 11

radioactive isotopes in biologically active molecules, traceable
-often used in medicine

Question 12

Radiometric Dating

Answer 12

measure the ratio of different isotopes; calculate age in years based on the number of half-lives (isotopes decay into daughter isotopes) have passed since organism was formed

Question 13

Valence Electrons

Answer 13

electrons that circulate the outer shell

Question 14

Chemical Bonds

Answer 14

Atoms share/transfer electrons

Question 15

Molecule

Answer 15

2 or More atoms chemically bonded

Question 16

Covalent Bond

Answer 16

2 atoms sharing the same electron to complete their valences

Question 17

Non-polar Covalent Bond

Answer 17

equal distribution of the electrons in a covalent bond

Question 18

Polar Covalent Bond

Answer 18

When one atom in an covalent bond is more electro-negative (don’t share their electron equally)

Question 19

Ionic Bond

Answer 19

Bond formed by electron transfer (rather than sharing), creating charges to both atoms involved
-attraction of cations and anions

Question 20

Ion

Answer 20

Charged atom

Question 21

Cation

Answer 21

Positively charged ion (Lost an electron)

Question 22

Anion

Answer 22

Negatively charged ion (Gained an electron)

Question 23

Salts

Answer 23

• Ionic Compounds

- Compounds formed by ionic bonds

Question 24

Hydrogen Bonds

Answer 24

When a Hydrogen atom (covalent) bonded to an electro-negative atom is attracted to a different electro-negative atom

Question 25

Chemical Reactions

Answer 25

making or breaking of bonds

Question 26

Reactants

Answer 26

the starting molecules of a chemical reaction

Question 27

Products

Answer 27

the final molecules of a chemical reaction

Question 28

Chemical Equilibrium

Answer 28

-when the forward and reverse chemical reactions happen at the same rate
(reactions offset one another exactly)
-concentrations don’t change, the rate of conversion is just equal

Question 29

Why do we need to study Chemistry when we are learning about Biology?

Answer 29

• Chemistry affects biology
• hormones, metabolism are examples of chemical processes within biology
• Biology is multidisciplinary
• Chemistry, Biology, Physics, etc. all occur naturally together. Need to learn the relationship

Question 30

What 5 elements make up the largest percentage of an organism’s mass? What elements are considered trace elements? Why?

Answer 30

• Oxygen, Nitrogen, Hydrogen, Carbon
• Potassium, Sulfur, Calcium, Phosphorous
• Trace elements are needed in small quantities
• H, C, O, N make up 96% of the body

Question 31

Atoms are composed of subatomic particles. What are these particles? How do we use these subparticles to identify elements?

Answer 31

• Protons, Neutrons, Electrons
• # of Protons is the Atomic Weight
• # of Protons determines what the element is

Question 32

All atoms of an element have the same number of protons, but may differ in the number of ____. Those atoms of the same element, but differ in the number of neutrons are called ______.

Answer 32

• Neutrons

- Isotopes

Question 33

The chemical behavior of an atom is mostly determined by its ______.

Answer 33

-Electrons

Question 34

What is the difference between a single convalent bond and a double covalent bond?

Answer 34

Single covalent bond: Share 1 pair of electrons

Double covalent bond: Share 2 pairs of electrons

Question 35

What type of bond is found in most of the strongest bonds in an organism’s cells?

Answer 35

-Covalent Bonds

Question 36

Why is the shape of a molecule important in Biology?

Answer 36

• Key to its function in a cell
• Key to brain function
• How the receptors recognize the necessary molecule
• Think of opiates and endorphins