Ch. 2

Question 1

Element

Answer 1

A substance that cannot be broken down to other substances. Matter is made up of elements.

Question 2

Compound

Answer 2

A substance consisting of 2 or more different elements. Combined in a fixed ratio. It has different characteristics than those of its elements.

Question 3

Essential elements

Answer 3

A chemical element required for an organism to survive, grow, & reproduce. Of the 92% natural elements, 20-25% are essential elements.

Question 4

What are the elements that make up 96% of living matter?

Answer 4

The element Oxygen, Carbon, Hydrogen, & Nitrogen. The remaining 4% is Calcium, Phosphorus, Potassium, & Sulfur.

Question 5

Atom

Answer 5

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

Question 6

Subatomic particles

Answer 6

Neutrons, protons, & electrons. They compose the atom.

Question 7

Where are the subatomic particles located?

Answer 7

Protons & neutrons in the nucleus. Electrons form electron clouds around the nucleus.

Question 8

Daltons

Answer 8

A measure of mass for atoms & subatomic particles; the same as the atomic mass unit of amu.

Question 9

Atomic number

Answer 9

The number of protons in nucleus of atom. It is written in as a subscript to the left of the element symbol.

Question 10

Mass number

Answer 10

The sum of protons & neutrons in the nucleus of an atom. Written to the left of element symbols as superscript.

Question 11

Atomic mass

Answer 11

The total mass of an atom.

Question 12

Isotopes

Answer 12

A variation of an element that has different number of neutrons, but still the same number of protons.

Question 13

Radioactive isotope

Answer 13

An isotope in which the nucleus decays spontaneously, giving of particles & energy.

Question 14

How to find number of neutrons in element?

Answer 14

Atomic mass - number of protons.

Question 15

Half-life

Answer 15

The amount of time it takes for 50% of a sample of a radioactive isotope to decay.

Question 16

Radiometric dating

Answer 16

A method for determining the absolute age of rocks & fossils based on the half life of radioactive isotopes.

Question 17

Energy

Answer 17

A capacity to cause change.

Question 18

Potential energy

Answer 18

The energy that matter possesses because of its location or structure.

Question 19

Electron shells

Answer 19

Energy levels where electrons are located.

Question 20

Valence electrons

Answer 20

Electrons in the outer most shell (valence shell). Determines reactivity. Full valence shell=chemically inert. Inert=chemically unreactive.

Question 21

Orbital

Answer 21

3rd space where electrons are found 90% of the time.

Question 22

Chemical bond

Answer 22

A mutual attraction between 2 atoms resulting from redistribution of outer electrons.

Question 23

Covalent bond

Answer 23

When elements bond by sharing electrons, a pair of valence electrons, by 2 atoms.

Question 24

Structural formula

Answer 24

Notation used to represent atoms & bonding. Ex. H-H, O=O.

Question 25

Molecular formula

Answer 25

Gives number of atoms of each element present. Ex. H2O.

Question 26

Valence

Answer 26

The bonding capacity of a given atom, usually equals the number of unpaired electrons required to complete the valence shell.

Question 27

Electronegativity

Answer 27

Measure of the tendency of an atom to attract a bonding pair of electrons. The more electronegative the atom is, the stronger it pulls shared electrons toward itself.

Question 28

Nonpolar covalent bond

Answer 28

A type of covalent bond in which electrons are shared equally between 2 atoms of similar electronegativity.

Question 29

Water is what kind of molecule?

Answer 29

Water is a polar molecule.

Question 30

Polar covalent bond

Answer 30

A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the electronegative atom.

Question 31

Ion

Answer 31

An atom or group of atoms that has gained or lost one or more electrons, thus acquiring change.

Question 32

Cation

Answer 32

A positively charged ion. To become a cation the atom has to lose electrons, therefore giving it an overall positive charge. Ex. K+, it loses an electron because it want to have the closest thing to a noble gas. The noble gas closest to it is Ar. So it has to lose an electron to have the same number of valence electrons.

Question 33

Anion

Answer 33

A negatively charge ion. The atoms gains electrons so it gives the atom an overall negative charge. Ex. Cl-, it gains an electron because it wants to be like Ar.

Question 34

Ionic bond

Answer 34

A chemical bond resulting from the attraction between oppositely charged ions.

Question 35

Ionic compounds

Answer 35

Compounds formed by ionic bonds.

Question 36

Hydrogen bond

Answer 36

A type of weak chemical bond that is formed when slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to a slightly negative atom of a polar covalent bond.

Question 37

Van der Waals interactions

Answer 37

Weak attractions between molecule or parts of molecules that result from transient local partial charges. Attractions between molecule that are close together.

Question 38

Reactants(reagents)

Answer 38

The things that react. The starting molecules of a chemical reaction.

Question 39

Product

Answer 39

What is produced from the reactants. The final molecules of a chemical reaction.

Question 40

What is conserved in a chemical reaction?

Answer 40

Matter is concerned in a chemical reaction. Relations cannot create or destroy atoms, but can only rearrange the electrons among them. All chemical reactions are reversible.

Question 41

Chemical equilibrium

Answer 41

The point which reactions off set one another exactly. When the forward and reverse reaction rates are equal.

Question 42

Chemical reaction

Answer 42

The making and breaking of chemical bonds.

Question 43

Matter

Answer 43

Anything that takes up space & has mass. Organisms are composed of matter.