Bonding 1 Flashcards
wcompound
substance made up of 2 or more different elements that are chemically combined eg carbon dioxide, water
octet rule
when bonding happens, atoms tend to reach an electron agreement with eight electrons in the outermost energy level. this is known as a stable outer octet.
valency
number of hydrogen atoms or any other monovalent element with which each atom of the element combines ie carbon can bond to 4 hydrogen atoms so its valency is 4
ionic bond
force of attraction between oppositely charged ions in a compound. they are always formed by the complete transfer of electrons from one atom to another. giving and receiving
transition metal
a metal that forms at least one ion with a partially filled d sublevel. it loses electrons from the 4s sublevel first
variable valency
there is a very small energy difference between the 4s and 3d sublevel so there can be movement of electrons between these sublevels which leads to ions with different charges. (ions can have more than one charge.)
how can you tell the charge on a transition metal?
by looking at its name (metals always form + ions) and the roman numerals give us the charge
what are the 2 elements not considered transition metals
scandium and zinc
why is scandium not considered a transition metal?
forms only 1 ion (Sc+3)
0 electrons in the 3d sublevel ie not partially filled
does not form coloured solution
why is zinc not considered a transition metal.
forms only 1 ion (Zn+2)
10 electrons in the 3d sublevel ie not partially filled
does not form coloured solution
which comes first when naming a compound
metal then the non metal
what is the name for a neg ion
anion
what is the name for a pos ion
cation
what sign is used to show an ionic bond in a diagram
an arrow
what must be shown outside of the brackets in an ionic bond diagram
the charge
what symbols are used to show electrons in ionic bonding diagrams
dots and crosses
what does a chemical formula tell us
how many atoms of each element there is in a compound
what charge do ionic compounds have?
neutral ie balanced
in what circumstances does crossing the charges on an ion not work?
if the numbers in the charges are the same (they cancel)
if the charges have a lowest common multiple ie 4 and 2 becomes 2 and 1
what are the steps in finding a chemical formula?
- what group is each element in
- decide what charge each ion has
- balance the charges by crossing the numbers
what is a polyatomic ion?
ions that have more than one atom
hydroxide
OH-
nitrate
NO3-
hydrogencarbonate
HCO3-
permagonate
MnO4-
carbonate
CO3-2
chromate
CrO4-2
dichromate
Cr2O7-2