CHAPTER TWO- CHEMISTRY OF BIOLOGY

Question 1

atomic number

Answer 1

number of protons found in the atoms nucleus

Question 2

atomic mass

Answer 2

average atomic mass of an elements isotopes, weighted by their abundance

Question 3

isotopes

Answer 3

Atoms with same atomic number (i.e. the same number of protons but different number of neutrons) but different atomic mass

Question 4

Electron shells

Answer 4

electrons move around the nucleus in designated areas called electron shells

Question 5

Atom stability

Answer 5

atoms become stable when their outermost shell is filled to capacity– stable atoms tend not to react or combine with other atoms

Question 6

Molecule

Answer 6

atoms that are held together by covalent bonds

Question 7

Covalent bonds

Answer 7

atoms share electrons on outermost electron shell

Question 8

Double covalent bonds

Answer 8

atoms share two pairs of electrons on outermost shells

Question 9

ionic bonds

Answer 9

one atom transfers one or more electrons completely to another– the result is two oppositely charged ions– the two oppositely charged ions attract each other forming an ionic compound – as long as there is no water present

Question 10

hydrogen bonds

Answer 10

an attraction between the slightly positively charged hydrogen atoms of one molecule and the slightly negative charged atom of another

Question 11

atom

Answer 11

smallest unit of matter that still retains the properties of an element

Question 12

one atom that easily forms covalent bonds

Answer 12

carbon

Question 13

Water

Answer 13

held together by covalent bonds– polar molecule

Question 14

Water is

Answer 14

a bent molecule, a polar molecule, forms hydrogen bonds, has strongly cohesive, high heat capacity, high surface tension, low density as a solid, evaporative cooling, good solvent

Question 15

Surface tension

Answer 15

the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of tis molecules & hydrogen bonds

Question 16

Heat capacity

Answer 16

water does not heat up fast– resists change in temperature — (1) heat from sun disrupts some of the hydrogen bonds between water molecules because water molecules start to move faster (2) new hydrogen bonds are formed almost as quickly as they are disrupted (3) energy breaks hydrogen bonds instead of increasing the water’s temperature