Biology Chapter 6

Front 1

Element

Back 1

Element: a substance that can't be broken down into simpler chemical substances.

Front 2

What four elements make up 96% of the mass of the human body?

Back 2

C, H, O, N

Carbon, Hydrogen, Oxygen and Nitrogen.

Front 3

Trace Elements

Back 3

Trace Elements: elements that play a vital role in maintaining healthy cells, but are needed in very small amount.

Front 4

Atoms

Back 4

Atoms are the smallest particle of an element that has the characteristics of that element.

Front 5

Atoms are refered to as the....

Back 5

building blocks of elements

Front 6

atom

Back 6

the smallest particle of an element that has the characteristics of that element.

Front 7

The structure of an atom:
(1-4)

Back 7

1. The center of an atom is the nucleus.

2. The nucleus is made up of protons which are positively charged and neutrons which are neutral or have no charge.
3. Elements are arranged on the Periodic table according to the number of protons they naturally have. This number is called the atomic number.
4. The region of space surrounding the nucleus contains extremely smal, negatively charged particles called electrons. This region is also kown as the electron cloud.

Front 8

Electron Cloud

Back 8

Electron Cloud: the regions of pace surrounding the nucleus... it contains extremely small, negatively charged particles called electrons

Front 9

Electron energy levels

(pg. 143, fig. 6.2)

Back 9

Within the electron cloud, there are energy levels which the electrons move around in.

Front 10

Isotopes of an element

Back 10

Isotopes are atoms of the same element that have the same number of protons, but a different numbers of neutrons.

Front 11

Scientist refers to isotopes by stating the combined total of?

Back 11

protons and neutrons in the nucleus.

Example:

Carbon-12 (naturally occurring element)

Carbon-14 (contains 2 more neutrons) it's nucleus is unstable and tends to break apart and give off radiation.

Front 12

Compound

Back 12

A compound is a substance that is composed of atoms of two or more different elements that are chemically combined.

Example NaCl

Front 13

How and why do elements combine?

Back 13

Atoms combine with each other only when the resulting compound is more stable than the individual atoms.

Front 14

When does an atom become stable?

Back 14

For many elements, an atom becomes stable when its outermost energy level is full.

Front 15

How do covalent bonds form?

Back 15

1. Covalent bonds is the force between two atoms that shar electrons.

2. The electrons being shared move around both elements holding them close together.

3. A molecule is a group of atoms held together by covalent bonds.
Example: Water (H2O)

Front 16

Covalent Bonds

Back 16

Covalent bonds is the force between two atoms that shar electrons.

Front 17

Ionic Bonds

Back 17

The attractive force between two ions of opposite charge.

Front 18

How do Ionic Bonds form?

Back 18

1. Ionic bonds: The attractive force between two ions of opposite charge.
2. Ion is a charged atom that gained or lost electrons.
3. These bonds are less abundant in living things than covalent molecules, but ions are important in biological processes. Example: Sodium & Potassium pumps conduct nerve impulses.
4. Example of Ionic Bonds: table salt NaCl

Front 19

Chemical Reactions

Back 19

Chemical reactions occur when bonds are formed or broken, causing substances to recombine into different substances.

Front 20

All the chemical reactions that occur within an organism are referred to as that organism's

Back 20

Metabolism

Front 21

How do you write a chemical equation?

Back 21

Basic setup: Reactant > Products

Example: Na + Cl > NaCl

Front 22

In chemical reactions it is important to understand that atoms are neither?

Back 22

created or destroyed, they are simply rearranged.

Front 23

Mixture

Back 23

A mixture is a combination of substances in which the individual components retain their own properties.

Example: mixing sand and sugar, salt and pepper.

Front 24

Solution

Back 24

A mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent).

In other words, one substance is dissolved in another and will not settle out of solution.

Example: Sugar and water, food coloring and water.

Front 25

What is a solute?

Back 25

A solute is the dissolved matter in a solution; the component of a solution that changes its state.

Front 26

What is a solvent?

Back 26

A solvent is a liquid substance capable of dissolving other substances; "the solvent does not change its state in forming a solution"

Front 27

The concentration of a solute is important to organisms because.........

Back 27

Organism's can not live unless the concentration of dissolved substances stays within a specific, narrow range.

Front 28

Chemical reactions can only occur when?

Back 28

Chemical reactions can only occur when conditions are right. On of the conditions that is very important is the pH of a solution.

Front 29

What is pH

Back 29

pH is the measure of how acidic or basic a solution is.

Front 30

pH scale

Back 30

The pH scale is a measure of how acidic or basic a solution is.

Front 31

Study pH Scale

Page 150, figure 6.11 for the pH scale

Back 31

Study pH Scale

Page 150, figure 6.11 for the pH scale

Front 32

An acid is any substance that forms?

Back 32

An acid is any substance that forms hydrogen ions (h) in water.

Example: HCI > H + Cl

Front 33

Base

Back 33

A base is any substance that forms hydroxide ions (OH) in water.

Example: NaOH . NA + OH

Front 34

If hydrogen ions equal the hydroxide ions the solution is neutral and has a pH of ?

Back 34

7

Front 35

If H > HO then the solution is?

Back 35

acidic

Front 36

If H > HO then the solution is?

Back 36

basic

Front 37

If H + OH then the solution is?

Back 37

neutral