unit 1+2 test Flashcards
mixture
mix of substances that have a variable composition; is classified as homogeneous or heterogeneous
relative formula mass
the ratio of the average mass per atom of the naturally occurring form of an element to one-twelfth the mass of an atom of carbon-12
empirical formula
chemical formula which gives the lowest whole number ratio of the atoms or moles of the element in a compound
molecular/covalent compound
compounds of elements made from a non metal + non metal
mole
aka Avogadro’s number; 6.02x10^23; unit of measurement for the amount of a chemical substance
physical property
something you can see/observe without a chemical change happening: ex. luster, color, volume, state, density, melting point, boiling point, shape, malleability
chemical change
bonds are broken and new bonds are formed; chemical composition changes: ex. color/odor, emission, heat, precipitate, light
periodicity
recurring variations in element properties with increasing atomic number
compound
substance composed of a given combination of elements that can be broken down into those elements by chemical methods; elements are always combined in the same proportions
group
vertical columns share similar properties bc they are organized by valence electrons
electron
negatively charged particles
significant figure
each of the digits of a number that are used to express it to the required degree of accuracy
molar mass
mass of one mole of a given substance
alkali metals
low-density, low-melting, highly reactive metallic elements
atom
smallest particle that makes up element
product
substance that is formed as the result of a chemical reaction
matter
stuff that has mass and takes up space; 3 states: solid, liquid, gas
scientific notation
method of expressing numbers in terms of a decimal number between 1 and 10 multiplied by a power of 10
properties of metals
good conductors of heat/electricity, shiny, solid at room temperature, ductile/malleable
law of conservation of mass
mass is neither created nor destroyed by chemical reactions or physical transformations; themassof the products in a chemical reaction must equal themassof the reactants
element
substance that can’t be broken down into other substances by chemical methods; each is unique
percent composition
percentage by mass of each element in a compound
reactant
a substance that takes part in and undergoes change during a reaction
molecular formula
equal to or whole number multiple of empirical formula
heterogenous
different
isotope
atoms of the same element has the same number of protons but different numbers of neutrons
periodic table
organized by atomic number
chemical property
something you can see only if substance is undergoing reaction: ex. acidity, reactivity, flammability
alkaline earth metals
react easily with other elements and are found in nature only in compounds
chemical equation
symbolic representation of a chemical reaction
ionic compound
compounds of elements made from a non metal + metal
distillation
transition of a substance directly from the solid to the gas phase without being a liquid
ion
a charged atom or group of atoms
abundance
amount of an isotope of an element that exists in nature
transition metals
Any of the metallic elements within Groups 3 through 12 in the Periodic Table; form alloys easily, have high melting points, and have more than one valence because of their incomplete inner shells
atomic number
number of protons an element has
physical change
chemical composition remains; change of one or more properties: ex. state change, color, density, volume
nucelus
holds protons and neutrons; electrons “orbit” around the outside
properties of nonmetals
poor conductors of heat and electricity, most are gases at room temperature, brittle, not metallic
pure substance
substances made of only one type of atom
halogens
nonmetallic; react readily with most metals to form salts
atom
smallest particle of an element that retains it’s identity
states of matter
different forms matter takes on; solid, liquid, gas, plasma
period
a set of elements occupying a row in the periodic table 9
proton
positively charged particles
noble gases
do not react chemically with other substances except under certain special conditions
homogeneous
the same
average atomic mass
average mass of one atom of a particular element
nucleon
a proton or neutron
neutron
neutrally charged particles
mass number
number of protons and neutrons an element has
polyatomic ion
charged ion composed of two or more atoms covalently bonded together
