Ch 2 The Chemical Context of Life

Question 1

Atoms are defined by their number of ___

Answer 1

Protons

Question 2

The atomic mass is the number of ___ plus ___

Answer 2

Protons + Neutrons

Question 3

Atomic number is the number of

Answer 3

Protons

and electrons when neutral

Question 4

Atoms that differ only in number of neutrons

Answer 4

Isotopes

Question 5

Something that is :

• Unstable
• Spontaneously emit particles and energy
• Can be useful in research and medicine

Answer 5

Radioactive Isotopes

Question 6

Position of electron determines its ____

Answer 6

Potential energy

Question 7

Electron shells that are farther from the nucleus _____

Answer 7

Increase in energy

Question 8

First electron shell holds ___ electrons

Answer 8

2

Question 9

Second and third electron shells hold ___ electrons each.

Answer 9

8

Question 10

Outer most electron shell is the ____

Answer 10

Valence Shell

Question 11

Electrons in outer most shell are ____

Answer 11

Valence electrons

Question 12

Covalent bonding results from the _________ of electrons between atoms

Answer 12

sharing

Question 13

Strongest type of bond in biological setting is ___

Answer 13

Covalent bond

Question 14

Define electronegativity

Answer 14

the relative attraction of an atom for electrons

Question 15

High electronegativity = _____

Answer 15

High attraction for electrons

Question 16

Electronegative atoms, most to least.

Answer 16

Oxygen, Nitrogen, Carbon = Hydrogen

Question 17

Polar Bond

Answer 17

Bond between atoms with different electronegativities

Question 18

Non-Polar Bond

Answer 18

Bond between atoms with similar electronegativities

Question 19

Ionic Bonding results from the ___ of electrons from one atom to another

Answer 19

Transfer

Question 20

Ionic bonding results in the formation of ____ , charged atoms or molecules.

Answer 20

Ions

Question 21

Cation

Answer 21

Positive charge

Question 22

Anion

Answer 22

Negative charge

Question 23

Ionic interactions

Answer 23

Are ionic bonds in water

Question 24

2 Requirements for a Hydrogen bond:

Answer 24

1. Hydrogen covalently bonded to a an electronegative atom (O or N)
2. Another electronegative atom (O or N)

Question 25

Strength of ionic bond in dry environment

Answer 25

Very strong

Question 26

Strength of ionic bond in water

Answer 26

Very Weak

Question 27

Occurs between a hydrogen with a partial positive charge and an electronegative atom.

Answer 27

Hydrogen bond