chemistry unit Flashcards
properties of ionic compounds :
high melting point
crystalline structure
solubility in water
form electrolytes
whats causes ionic compounds to have a high melting point
the attraction between cations and anions forms a strong crystalline structure.
what happens to the crystalline structure of ionic compounds when ground into a fine powder?
they retain their structure even when ground into a fine power.
why are ionic compounds soluble in water?
cations are strongly attracted to the negative end of water molecules, and anions are strongly attracted to the positive end of water molecules.
what makes a substance more conductive
a stronger concentration of ions does.
one molecule prefix
mono
two molecule prefix
di
three molecule prefix
tri
four molecule prefix
tetra
five molecule prefix
penta
six molecule prefix
hexa
seven molecule prefix
hepta
eight molecule prefix
octa
nine molecule prefix
nona
ten molecule prefix
deca
how to determine the state of an element
indicated by the element box on the periodic table.
how to determine the state of a molecular compound
must memorize common molecular compounds.
how to determine the state of an ionic compound in an aqueous environment.
use solubility table.
ammonia chemical formula
NH3(g)
glucose chemical formula
C6H12O6(s)
hydrogen peroxide formula
H2O2(l)
sucrose formula
C12H22O11(s)
methane formula
CH4(g)
ethane formula
C2H6(g)
propane formula
C3H8(g)
methanol formula
CH3OH(l)
ethanol formula
C3H5OH(1)
water high melting and boiling points cause
it takes large amounts of energy to break hydrogen bonds.
water high surface tension causes
hydrogen bonds hold water at the surface tightly together
polar meaning
uneven distribution of electrons
concave meniscus causes water
polar water molecules are attracted to the sides of the container
capillary action
cohesive and adhesive properties of water result in water being attracted to the sides of the tube and to each other. this results in water being pulled up the tube
why does ice float
hydrogen bonding causes solid water to form a six-sided crystal that is less dense than the liquid.
why is water a universal solvent?
polarity causes water to be attracted to the positive and negative charges present in other substances, allowing them to dissolve easier.
hydrogen bond
dipole, dipole attraction between molecules. not a covalent bond.
diatomic elements
hydrogen, nitrogen,oxygen,fluorine,chlorine, bromine, iodine.
polyatomic elements + how many they have.
phosphorus ( 4), sulfur (8)
how is a molecular compound different from an ionic compound
a molecular compound is composed of 2 or more nonmetals joined by covalent bonds ( electrons shared). an ionic compound is composed of a metal and a non metal joined by an ionic bond. in an ionic compound electrons are transferred resulting in the formation of ions which are attracted to each other.
are polyatomic ions molecular?
yes because they are composed of non-metals joined by a covalent bond.
traits of molecular compounds
1) form non electrolytic solutions when dissolved in water ( because they do not have ions ).
2) low solubility
3) relatively low melting and boiling points.
4) require large amounts of energy to decompose. ( due to strong covalent bonds ).
5) can form crystals but crumble easily.
how to find neutrons
subtract atomic number from atomic mass
group 1 , alkali metals
soft, shiny, silver, highly soluble. reactive in water.
alkaline earth metals ( group 2)
shiny and silver. not as soft or soluble as group 1.
halogens ( 17)
highly reactive. poisonous. get less reactive as you go down the group.
noble gas, group 18
non-reactive due to a stable valence shell.
metal traits
silver or grey in color, shiny, malleable, ductile, good conductors of heat and electricity, most solid at room temp.
traits of non metals
may be solid, liquid or gas at room temp. typically poor conductors of electricity and heat.
metalloids traits
mixed traits of metals and non metals.
how many electrons does the first level hold
2
how many electrons does the second level hold
8
how many electrons does the third level hold
8
how many electrons does the fourth level hold
12
cation
positively charged ion that forms when an atom ( usually a metal ) loses an electron.
anion
negatively charged ion that forms when an atom ( usually a non metal)
gains an electron.
ion
charged atom or group of atoms
isotopes
atpms of the same element that contain different numbers of neutro s. because of this they have different charges.
the atomic mollar mass is the average of all the elements isotopes.
the most common isotope of each element is found by rounding the mass number found on the periodic table.
can protons change
no
ionics bonds
the cation ( one that loses an electron) and anion are attracted to each other by charge.
rules for writing formulas of binary ionic compounds
write cation symbol first. determine charges needed to balance then add coefficients.
poly atomic elements
phosphorus ( 4), sulfur ( 8 ), oxygen ( 2), oxygen can also have 3 in some cases. hydrogen ( 2), nitrogen( 2), fluorine (2), chlorine ( 2), bromine ( 2) , and iodine (2)
how many atoms are in sulfur?
sulfur has 8 atoms
how many atoms are in phosphorus?
sulfur has 4 atoms.
multivalent element cation charge.
when only given the chemica formula use the
how many electrons does the fourth level hold.
it holds 18.
