unit 1.1 - formulae and equations Flashcards

Question

Hydrogen

Answer 1

the number given to an atom in a molecule or an ion based on the number of electrons this atom uses in chemical bonding

Answer 2

the number of electrons that need to be added (or taken away from) an element to make it neutral.

Answer 3

calcium ion, Ca2+ needs two electrons added to it in order to make a neutral calcium atom. Its oxidation number is therefore +2 (add 2 electrons). A sulphide ion, S2-, needs to lose two electrons in order to make a neutral sulfur atom. Its oxidation number is therefore -2 (take 2 electrons away).

Answer 4

calcium ion, Ca2+ needs two electrons added to it in order to make a neutral calcium atom. Its oxidation number is therefore +2 (add 2 electrons). A sulphide ion, S2-, needs to lose two electrons in order to make a neutral sulfur atom. Its oxidation number is therefore -2 (take 2 electrons away).

Answer 5

An uncombined element has an oxidation number of zero

Answer 6

Group 1 elements in all compounds oxidation number = +1

Answer 7

Group 2 elements in all compounds the oxidation number =+2

Answer 8

Hydrogen in most compounds oxidation number is +1

Answer 9

Oxygen is most compounds oxidation number is -2

Answer 10

the sum of oxidation number of a compound must = 0

Answer 11

the sum of the oxidation number of a compound must = 0

Answer 12

the halide ions oxidation number in an ionic compounds equal -1 Br-1, cl -1

Answer 13

oxidation - loss of electrons + Reduction - gain of electrons -

Answer 14

* *C*O2 - (-2x2) = -4 so c has to be -4 to add up to 0 * Cu20 - (-2) so cu has to be +2 so cu =+1 * *Al*Cl3 = cl = -1 x 3 = -3 so Al = +3 * *P4*010 = P = -2x10 = 20 so P4 has to be +20 so p = 5 * *s*04^2- = has to add up to -2 so -2x4 = -8 so s has to be +6 * I2 = 0 uncombined element = 0 * *N*03 - = has to add up to -1. O = -2 x3 = -6 N has to add up to +5 * *Mn*04- has to add up to -1. O = -2 x 4 = -8. Mn = +7 | stars represent italics which represent which represents which one i wa

Answer 15

written to sum up what happens in a chemical reaction using chemical formulae a full complete equation can be converted into an ionic equation involves ionic compounds when ions react with each other

Answer 16

because they appear on both sides of the equation into equal amounts

Answer 17

H2S04(aq) + 2NaOH(aq) ----------- Na2SO4(aq) + 2H20(l) 2H+ + SO42 +2na+OH- ------------- 2Na+ + S042- +2H20 2H+ 2OH- ------ 2 H20 H+(aq) + OH-(aq) -------- H20(l)

Answer 18

Mg(s) + 2HCl(aq) ----------- MgCl2(aq) + H2(g) Mg(s) +2H+ + 2Cl- ---------Mg2+(aq) + 2Cl-(aq) +H2(g) Mg(s) + 2H+(aq) ------------ Mg2+(aq) +H2(g)

Answer 19

2KB(a q)r +Cl2(aq) ------------- 2KCl(aq)+Br2(aq) 3K + 2Br- +Cl2 ---------------- 2K + 2Cl - +Br2 2Br-(aq) +Cl2(aq) --------------2Cl-(aq) + Br2(aq)

Answer 20

HCl (aq) + NaOH (aq) → NaCl (aq) + H2O (l) H+(aq) + Cl- (aq) + Na+ (aq) + OH- (aq) → Na+ (aq) + Cl- (aq) + H2O (l) H+ (aq) + OH- (aq) → H2O (l)

Answer 21

state symbols have to be used in ionic equations. If you look carefully at the state symbols for all of the ionic equations above, you will see that: - ∙ The products are never aqueous – above you have a liquid and two solids. ∙ Spectator ions are the ones that remain in aqueous solution.