Life Requires About 25 Chemical Elements

Question 0

Element required by an organism in extremely minute quantities. Though in small quantities, are indispensable for life.

Answer 0

Trace element

Question 1

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

• all matter made of this
• 92 naturally occurring
• designated by a symbol of one/two letters

Answer 1

Element

Question 2

Element required by an organism in extremely minute quantities but TOXIC at high levels. Ex. Arsenic (Ar)

Answer 2

Ultratrace element

Question 3

A pure substance composed of two or more different elements combined in a fixed ratio. Ex. NaCl (sodium chloride)

Answer 3

Compound

Question 4

Smallest possible unit of matter that retains (keeps) the physical and chemical properties of its element.

Answer 4

Atom

Question 5

The three most stable subatomic particles are?

Answer 5

Neutron, protons, electrons

Question 6

Two opposites attracting each other.

Answer 6

Electrostatic

Question 7

A measurement of mass at the atomic level

Answer 7

Dalton

Question 8

Number of protons in an atom of a particular element. All atoms of an element have the same one.

Answer 8

Atomic number

Question 9

Number of protons and neutrons in an atom. Each has a mass of approx. 1 dalton. Can deduce the number of neutrons by subtracting atomic number from atomic mass.

Answer 9

Mass number

Question 10

Anything with a positive charge– loses electron

Answer 10

Cation

Question 11

Anything with a negative charge–gains electron

Answer 11

Anion

Question 12

Atoms of an element that have the same atomic number but different mass number. Protons don’t change only the neurons. Some of these are radioactive.

Answer 12

Isotopes

Question 13

Weighted average of the mixture.

Answer 13

Atomic weight

Question 14

Unstable(start to break down) isotopes in which the nucleus spontaneously decays emitting subatomic particles and/or energy as radioactivity.

Answer 14

Radioactive isotopes

Question 15

Time for 50% of radioactive atoms in a sample to decay. How does it take for half of it to be gone.

Answer 15

Half life.

Question 16

Chemicals labeled with radioactive isotopes are used to trace the steps of a biochemical reaction or to determine the location of a particular substance within the organ. Used to diagnose disease (e.g. PET scanner).

Answer 16

Radioactive tracers

Question 17

An example of a treatment for cancer

Answer 17

Radioactive cobalt

Question 18

Light negatively- charged particles that orbit around a nucleus. Are the only subatomic particles which are directly involved in chemical reactions

Answer 18

Electrons

Question 19

Ability to do work.

Answer 19

Energy

Question 20

Energy that matter stores because of its position or location

Answer 20

Potential energy

Question 21

Distribution of electrons in an atoms electron shell.

Answer 21

Electron configuration

Question 22

Electrons in the outermost energy shell.

Answer 22

Valence electrons

Question 23

Chemical properties of an atom depend upon the number of what?

Answer 23

Valence electrons

Question 24

Rule that a valence shell is complete when it contains 8 electrons.

Answer 24

Octet rule

Question 25

Have filled outer shells in their elemental state and are thus inert.

Answer 25

Noble elements

Question 26

Attractions that hold molecules together.

Answer 26

Chemical bonds

Question 27

(2+) atoms held together via chemical bonds

Answer 27

Molecule

Question 28

Like a molecule but must contain (2+) different atoms

Answer 28

Compound

Question 29

Are chemical bonds formed by sharing a pair of valence electrons.

Answer 29

Covalent bonds