random Flashcards
The particle represented by the symbol Y2+ with the mass no. 89 and the atomic no. 39 contains?
39 protons, 50 neutrons and 37 electrons.
mass no. - atomic no. (89 - 39) = no. of neutrons (50)
atomic no. (39) = no. of protons (39)
since it is an cation there are less electrons than protons
so no. of protons (39) - 2 (since its 2+) = 37 electrons
if an element is a anion are there more electrons or protons?
there are fewer protons than electrons
if an element is a cation are there more electrons or protons?
there are fewer electrons than protons
how do we know what period an element is located in?
by looking at the amount of shells taken up by the electron configuration
eg 2, 8, 5 - three shells used so period 3
how do we know what group an element is located in?
by looking at the amount of valence electrons
eg 2,8,5 would be group 15
but 2,3 would be in group 13
and 2,8,8,2 would be in group 2
A neutral atom of element X has the electron configuration 2,8,18,2.
Given this information, it would be incorrect to say that element X
would be located in Period 3 of the Periodic Table.
because it has 4 shells therefore it should be in period 4.
define the following:
endothermic reaction
combustion reaction
displacement reaction
neutralisation reaction
endothermic - absorbing heat from its surroundings
combustion - burning
displacement - A more reactive metal will displace or push out a less reactive metal from its compound in a displacement reaction.
neutralisation reaction - an acid and alkali will neutralise each other and produce a salt and water.
why would this pair of these elements be most likely to form an ionic bond?
2,8,2 and 2,8,6
bc to fill the 2nd elements last electron shell it would need 2 electrons which the first shell has
how many bonds do different elements like to form?
C - 4 valence therefore 4 bonds
N - 5 valence therefore 3 bonds
O - 6 valence therefore 2 bonds
F - 7 valence therefore 1 bond
elements on the right side of the periodic table like to “acquire” electrons therefore the no. of valence electrons and bonds add up to 8, elements to the left of carbon like to give up their electrons so the no of valence electrons corresponds with the no. of bonds
eg B - 2 valence 2 bonds
Be - 3 valence 3 bonds
how to draw lewis structures?
try out H2O and NH3 and O2
1. determine the no. of valence electrons
2. space out electrons evenly around element symbol before pairing
(halogens like to form single bonds)
3. use knowledge of elements and their bonds to create a diagram showing only the covalent bonds.
If, instead, sodium metal is placed in a concentrated sulfuric acid solution and then heated would you expect this reaction to be more or less reactive than the reaction with aluminium metal outlined above? Give a reason to justify your answer.
more reactive, bc it is higher up on the reactivity scale of metals as it is in group 1 whereas Al is in group 2 making Na more reactive
what is the balanced chemical formula for iron metal and iron (111) metal
Fe
and Fe subscript 3
what does it mean by delocalised electrons
“free” or detached from a particular thing
covalent bonding can be:
simple covalent (most covalent compounds)
eg chlorine
hydrogen chloride
water
oxygen
giant covalent (few covalent compounds)
dimond
graphite
graphene
non metals share electrons; covalent bond = shared pair of electrons
ionic bonding
both metals and non metals
metals and non metals gain and loose electrons
Ionic bond - strong electrostatic attraction between positive and negative ions
ionic compound egs
calcium chloride
magnesium oxide
