Chemistry for Biology

Biology ~ Edgar

True or False

• Table salt, water, and carbon are all compounds.

• The smallest particle of an element is a molecule.

• A bathtub full of lukewarm water may hold more heat than a teakettle full of boiling water.

• If the atoms in a molecule share electrons equally, the molecule is said to be non-polar.

• Ice floats because water molecules in ice are more tightly packed then in liquid water.

• Atoms in a water molecule are held together by the sharing of electrons.

• If solution-A has a pH of 2 and solution-B has a pH of 5 then solution-B is a stronger base then solution-A

• An atom that has gained or lost electron is called an ion.

• Hydrogen bonds are stronger then covalent bonds.

• Water is a good solvent in living organisms.

Figure 2.1 The hierarchy of biological order from atom to organism

Table 2.1

LE 2-3

Sodium Chlorine Sodium Chloride

Figure 2.5 Two simplified models of a helium (He) atom

LE 2-4a

2

2

2

Protons

Neutrons

Electrons

Helium atom

Massnumber = 4

6

6

6

Protons

Neutrons

Electrons

Carbon atom

Massnumber = 12

Electroncloud

Nucleus

2e–

6e–

Figure 2.10 Electron configurations of the first 18 elements

Figure 2.12x Methane

Figure 2.12 Covalent bonding in four molecules

LE 2-6b

Nitrogen (N)Atomic number = 7

Oxygen (O)Atomic number = 8

LE 2-9

A water molecule

Figure 2.16 A hydrogen bond

Figure 2.15 A sodium chloride crystal

LE 2-7a-1

Transfer ofelectron

NaSodium atom

ClChlorine atom

LE 2-7a-2

Na

Sodium ionCl

Chloride ion

Sodium chloride (NaCl)

LE 2-7b

Na

Cl

LE 2-10

Hydrogen bond

Figure 2.11

Figure 2.12

LE 2-13

Hydrogen bond

Ice

Hydrogen bonds are stable

Liquid water

Hydrogen bondsconstantly break and re-form

LE 2-14

Ion insolution

Saltcrystal

Trees and Water Transport

LE 2-15

Acidic solution

OH

H

HH

HOH

H H

H

OH

OH

OH

OH

OH

H

H

H

H

HH

I ncr

ea

sin

gl y

AC

IDI C

(Hi g

he

r c

on

c en

tra

t io

n o

f H

)Neutral solution

OH

OH

OH

OH

OH

OH

H

H

Basic solution

NEUTRALH

pH scale

Lemon juice, gastric juice

Grapefruit juice, soft drink

Tomato juice

Human urine

Pure water

Human blood

Seawater

Milk of magnesia

Household ammonia

Household bleach

Oven cleaner

Incr

ea

sin

gl y

BA

SIC

(Lo

we

r c

on

cen

tra t

i on

of

H )

Figure 2.16a

Figure 2.16b