Chapter 2

Question 1

Organisms are composed of matter, which is:

Answer 1

Anything that takes up space and has mass.

Question 2

An element:

Answer 2

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

Question 3

Matter is made up of…

Answer 3

Elements

Question 4

How many elements are recognized in nature by chemists today?

Answer 4

92

Question 5

A compound is:

Answer 5

A substance consisting of two or more different elements combined in a fixed ratio

Question 6

How much of the 92 natural elements are essential for a healthy life and reproduction?

Answer 6

20 to 25%

Question 7

Trace elements:

Answer 7

Required by an organism in only minute quantities

Question 8

Atoms:

Answer 8

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

Question 9

Adams are composed of even smaller parts called:

Answer 9

Subatomic particles

Question 10

Each proton has one unit of…

Answer 10

Positive charge

Question 11

Each electron has one unit of…

Answer 11

Negative charge

Question 12

Atomic number

Answer 12

The number of protons in the nucleus of a particular element.
Written as a subscript to the left of the symbol for the element.

Question 13

Mass number:

Answer 13

The number of protons and neutrons in the nucleus of an atom.
Written as a subscript to the left of an element symbol.

Question 14

The number of neutrons in the nucleus of an atom can be determined by:

Answer 14

Subtracting the atomic number from the mass number

Question 15

Isotopes

Answer 15

Different atomic forms of the same element.

Question 16

Stable isotopes

Answer 16

Nuclei do not have a tendency to lose it subatomic particles.

Question 17

Radioactive isotope

Answer 17

Nucleus decays spontaneously, giving off particles and energy.

Question 18

Half-life of the isotope:

Answer 18

The time it takes for 50% of the parent isotope to decay.

Question 19

Energy is defined as:

Answer 19

The capacity to cause change

Question 20

Potential energy

Answer 20

The energy that matter possesses because of its location or structure

Question 21

Matter has a natural tendency to move toward the…

Answer 21

Lowest possible state of potential energy

Question 22

Electrons have potential energy due to their…

Answer 22

Distance from the nucleus

Question 23

The more distant an electron is from the nucleus, the…

Answer 23

greater its potential energy.

Question 24

And electrons potential energy is determined by…

Answer 24

Its energy level.

And electron can only exit at certain energy levels, not between them.

Question 25

An electron can move from one shell to another, but only by...

Answer 25

Absorbing or losing an amount of energy equal to the difference in potential energy between its position in the old shell and that in the new shell.

Question 26

When an electron absorbs energy:

Answer 26

It moves to a shell farther out from the nucleus

Question 27

When an electron loses energy:

Answer 27

It falls back to a show closer to the nucleus, lost energy is usually released to the environment as heat.

Question 28

The chemical behavior of an Atom depends mostly on:

Answer 28

The number of electrons in its outer most shell

Question 29

Valance electrons

Answer 29

Electrons in the outer shell

Question 30

Valance shell

Answer 30

The outer most electron shell

Question 31

Atoms with the same number of electrons in their valance shells...

Answer 31

Exhibit similar chemical behavior

Question 32

And atom with a completed valance shell is:

Answer 32

Unreactive; will not interact readily with other atoms

Question 33

Inert

Answer 33

Chemically unreactive

Question 34

Orbital

Answer 34

The three-dimensional space where an electron is found 90% of the time

Question 35

Covalent bond

Answer 35

Sharing of a pair of balance electrons by two atoms

Question 36

Two or more atoms how together by covalent bonds constitute a...

Answer 36

Molecule

Question 37

Compound

Answer 37

A combination of two or more different elements

Question 38

Electronegativity

Answer 38

The attraction of a particular Atom for the electrons of a covalent bond.

Question 39

A nonpolar covalent bond

Answer 39

A covalent bond between two atoms of the same element, electrons are shared equally because the two atoms have the same electronegativity

Question 40

A polar covalent bond

Answer 40

When an atom is bonded to a more electronegative atom. Electrons are not shared equally.

Question 41

Ions

Answer 41

The two resulting oppositely charged atom or molecules. Two atoms are so an equal in their attraction for a valance electron is that the more electronegative atom strips an electron completely away from his partner.

Question 42

A positively charged ion is called

Answer 42

An cation

Question 43

A negatively charged ion is called

Answer 43

An anion

Question 44

An ionic bond

Answer 44

Is formed due to the opposite charges, cations and anions which attract each other.

Question 45

Hydrogen bond

Answer 45

Hydrogen atom is covalently bonded to a electron negative atom, the hydrogen atom has a partial positive charge that allows it to be attracted to a different electronegative atom nearby.

Question 46

In living cells, the electronegative partners of the partially positive charged hydrogen atom are usually:

Answer 46

Oxygen or nitrogen atoms