Praxis Middle School Science-The Mole and Chemical Bonding Flashcards
mole
that number whose mass in grams is numerically equal to the atomic mass, molecular mass, or formula mass of the substance
why do we have the mole?
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.
avogrado’s number
the number of atoms, ions, molecules or anything else in one molecule, or 6.02 x 10^23
law of definite proportions (law of constant composition)
a pure compound, whatever its source, always contains definite or constant proportions of the elements by mass
it is a fixed composition
mixture
a material that can be separated by physical means into two or more substances
mixtures are classified into two types
- heterogeneous mixture: a mixture that consists of physically distinct parts, each with different properties. ex: chex mix.
- homogeneous mixture: (solution) a mixture that is uniform in its properties throughout a given sample.
formula
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.
reacants
are found on the left side of the equation
products
found on the right side of the equation
chemical reaction
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
chemical equilibrium
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
example of chemical equilibrium
C + O2 –> CO2
no matter is ever _________ or ________ in a chemical reaction.
gained or lost
therefore, the chemical equation must be balanced
ionic compounds are named with the ____ first
cation
cation
positive ion
nearly all cations in inorganic chemistry are
monatomic, meaning they consist of just one atom and are formed from a metal ion.
anion
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.
oxoanions
contain one element in combination with oxygen
end in the suffix –ate.
water molecules often occupy positions within
the lattice of an ionic crystal, called hydrates.
molecular compounds
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
prefixes indicating numbers
1- mono 2- di 3- tri 4- tetra 5- penta 6- hexa 7- hepta 8- octa 9- nona 10- deca
hydrocarbons
the simplest organic compounds, containing only carbon and hydrogen
alkanes
a hydrocarbon compound containing only single bonds
saturated
describing a hydrocarbon like an alkane that has the maximum number of hydrogen atoms possible for its carbon backbone
