Praxis Middle School Science-The Mole and Chemical Bonding

Question 1

mole

Answer 1

that number whose mass in grams is numerically equal to the atomic mass, molecular mass, or formula mass of the substance

Question 2

why do we have the mole?

Answer 2

a single atom or molecule weighs so little that it cannot be measured using a balance in the lab.

it is useful to have a system that permits a large number of chemical particles to be described as one unit.

Question 3

avogrado’s number

Answer 3

the number of atoms, ions, molecules or anything else in one molecule, or 6.02 x 10^23

Question 4

law of definite proportions (law of constant composition)

Answer 4

a pure compound, whatever its source, always contains definite or constant proportions of the elements by mass

it is a fixed composition

Question 5

mixture

Answer 5

a material that can be separated by physical means into two or more substances

Question 6

mixtures are classified into two types

Answer 6

1. heterogeneous mixture: a mixture that consists of physically distinct parts, each with different properties. ex: chex mix.
2. homogeneous mixture: (solution) a mixture that is uniform in its properties throughout a given sample.

Question 7

formula

Answer 7

a shorthand that uses symbols and subscripts to show what is in a compound.

the letter symbols tell us what elements are involved.

the number signs tell us how many of each element are involved.

Question 8

reacants

Answer 8

are found on the left side of the equation

Question 9

products

Answer 9

found on the right side of the equation

Question 10

chemical reaction

Answer 10

a chemical event in which one or more substances are formed.

energy is released. energy release can be slow or rapid.

ex: rapid= fireworks
slowly= the tarnishing of a spoon

Question 11

chemical equilibrium

Answer 11

state reached when the quantities of reactants and products are no longer shifting, but the reaction may still proceed with equal forward and backward reaction

Question 12

example of chemical equilibrium

Answer 12

C + O2 –> CO2

Question 13

no matter is ever _________ or ________ in a chemical reaction.

Answer 13

gained or lost

therefore, the chemical equation must be balanced

Question 14

ionic compounds are named with the ____ first

Answer 14

cation

Question 15

cation

Answer 15

positive ion

Question 16

nearly all cations in inorganic chemistry are

Answer 16

monatomic, meaning they consist of just one atom and are formed from a metal ion.

Question 17

anion

Answer 17

negative ion

named and written last

they’re formed from nonmetallic elements and are named by replacing the end of the element’s name with the suffix –ide.

Question 18

oxoanions

Answer 18

contain one element in combination with oxygen

end in the suffix –ate.

Question 19

water molecules often occupy positions within

Answer 19

the lattice of an ionic crystal, called hydrates.

Question 20

molecular compounds

Answer 20

compounds (usually composed entirely of nonmetals) making up molecules with a neutral charge

they’re named by placing the less electronegative atom first.

the suffix –ide is added to the second, more electronegative atom

Question 21

prefixes indicating numbers

Answer 21

1- mono
2- di
3- tri
4- tetra
5- penta
6- hexa
7- hepta
8- octa
9- nona
10- deca

Question 22

hydrocarbons

Answer 22

the simplest organic compounds, containing only carbon and hydrogen

Question 23

alkanes

Answer 23

a hydrocarbon compound containing only single bonds

Question 24

saturated

Answer 24

describing a hydrocarbon like an alkane that has the maximum number of hydrogen atoms possible for its carbon backbone

Question 25

unsaturated

Answer 25

describing a hydrocarbon like an alkene that has fewer than the maximum number of hydrogen atoms possible

Question 26

alkenes

Answer 26

also called olefins, are hydrocarbons that contain one or more double bonds.

Question 27

alkynes

Answer 27

hydrocarbons that contain one or more triple bonds.

Question 28

alkelynes

Answer 28

hydrocarbons with double and triple bonds.

Question 29

aromatic hydrocarbons

Answer 29

hydrocarbons that structurally are related to benzene or made of benzene molecules fused together

called arenes

all atoms lie in the same plane, they are flat.

electrons are free to migrate throughout the molecule

Question 30

hydrogen bond

Answer 30

the weakest of the three types of chemical bonds

formed when one electronegative atom shares a hydrogen atom with another electronegative atom

ex: water bonding with ammona (NH3)

Question 31

valence electrons

Answer 31

outermost electrons

they are involved in the bonding process

they determine the properties of the element

Question 32

chemical bonds are formed when

Answer 32

atoms with incomplete valence shells share or completely transfer their valence electrons

Question 33

condensed structural formulas

Answer 33

a representation of a chemical compound: the elemental atoms and their sub/superscripts

ex: ethanol is CH3CH2OH

Question 34

line angle drawings

Answer 34

a representation of a chemical compound: angled lines that intersect and terminate with the designated elements

Question 35

lewis dot structure

Answer 35

a method for keeping track of each atom’s valence electrons in a molecule