chemistry 2 lesson 1.3 ions aqa additional science
TRANSCRIPT
Aims
Class work 29 June 2007Ions
LO’s• What are ions?
Write it down!! Page 43/44© C Meyer
All• Know elements react to form
compounds• Know the layout of the periodic
table• Know what an ion is• Know group 1 reacts with Group 7Most/Some• Explain how ions form• Work out the charge on an ion
Aims
• What are the properties of Sodium?
• What are the properties of Chlorine?
What are ions?
Demo Na/Cl reaction to make salt
Metal, solid, left hand side of Periodic table, 11 protons,
Electronic structure = 2, 8, 1
Non - metal, gas, right hand side of Periodic table, 17 protons,
Electronic structure = 2, 8, 7
m3
• Any element from left hand side of table reacts with element from right
• 1 use of periodic table – predict reactions
What are ions?
K
Al P SSiMgNa ArCl
Be N OB CLi NeF
reactive gases
reactive metals
Elements
• Elements are the simplest substances. There are about 100 different elements N
S
OC
Fe
K
NN
N
N
N N
NN
• Each elements has just one particular type of atom that is different to the atoms in any other element
• Even in elements atoms usually join (bond) together.
• In some elements atoms bond to form small simple structures.
• In other elements atoms bond into giant structures with millions of atoms.
Compounds
• Compounds are formed when different elements chemically react together.
• In these reactions different types of atom become chemically bonded.
• Like elements some compounds have small simple structures with just a few atoms bonded together
• Others compounds have large, complex structures containing thousands or even millions of bonded atoms.
OH H
Water – a simple structure
DNA – a large & complex structure
Compounds are not just mixtures
• Reacting is different to just mixing.• The physical and chemical properties of compounds are
veryvery different to their original elements.
Sodium + Chlorine Sodium Chloride
COMPOUNDELEMENTS
Na Cl Cl Na Cl
(silver solid) (green, poison gas)
(Salt, flavours chips)
Mixture – sand and salt, easy to separate (filter)
Copy the Table and fill in the last column.
SiO2Sand
HgMercury
Fe2O3Rust
O2Oxygen
H2OWater
CuSO4Copper sulphate
NiNickel
NaClSodium chloride
Element or compound
FormulaName
compound
element
compound
compound
element
compound
element
compound
Rust consists of
iron combined
with oxygen
Activity
Arranging elements
K
He
Al P SSiMgNa ArCl
Be N OB CLi NeF
When elements are arranged according to their properties what patterns do you see and what element is missing?
reactive metals
unreactive gases
reactive gases
Similar elements go into the same columns.
Hydrogen is an exception. This reactive gas is best positioned above the reactive metals.
Hhydrogen is a special case
The periodic table
Arranging all the elements by atomic number and properties led to the creation of…
the periodic table
H He
Fr Ra Rf Db Sg Bh Hs Mt ? ?Ac ?
K Ca Ga Ge As Se KrSc Ti V Cr Mn Fe Co Ni Cu Zn Br
Cs Ba Tl Pb Bi Po RnHf Ta W Re Os Ir Au HgLa Pt At
Na Mg Al Si P S ArCl
Li Be B C N O NeF
Rb Sr In Sn Sb Te XeY Zr Nb Mo Tc Ru Pd Ag CdRh I
Columns of elements
H
Li
Na
K
Rb
Cs
Fr
Be
Mg
Ca
Sr
Ba
Ra
Ga
In
Tl
Al
B
Ge
Sn
Pb
Si
C
Sb
Bi
P
N
As Se
Te
Po
O
S
He
Kr
Ne
Ar
Rn
Xe
Sc Ti V Cr Mn Fe Co Ni Cu Zn
Y Zr Nb Mo Tc Ru Pd Ag CdRh
Hf Ta W Re Os Ir Au HgLa Pt
Rf Db Sg Bh Hs Mt ? ?Ac ?
Br
At
Cl
F
I
What are columns of elements called?
765432
GroupsGroups
1 0Group number
transition elements
Rows of elements
H He
Li Be N O F NeB C
Na Mg Al P S Cl ArSi
K Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge Se BrCa KrAs
Rb Y Zr Nb Mo Tc Ru Pd Ag Cd In Sn SbSr TeRh I Xe
Cs Ba Hf Ta W Re Os Ir Au Hg Tl Pb Bi PoLa AtPt Rn
Fr Ra Rf Db Sg Bh Hs Mt ? ?Ac ?
PeriodsPeriodsWhat are rows of elements called?
1
2
3
4
5
6
7
Period number
H He
Li
Na
K
Rb
Cs
Fr
Be
Sc Ti
Mg
V Cr Mn Fe Co Ni Cu Zn Ga Ge Se BrCa Kr
Y Zr Nb Mo Tc Ru Pd Ag Cd In Sn SbSr TeRh
Ba Hf Ta W Re Os Ir Au Hg Tl Pb Bi PoLa AtPt
Ra Rf Db Sg Bh Hs Mt ? ?Ac ?
Al P
N O
S Cl
F Ne
Ar
Rn
I
Si
Xe
B C
As
What is the Group and Period of this element?
Mg
C
Group 2 Group 4Group 7
Cl
K
Group 1MgCClK
Name the position
7654321 0
2
3
4
5
6
7
Period 3Period 2Period 3Period 4
1
H1 He
Li
Na
K
Rb
Cs
Fr
Be
Sc Ti
Mg
V Cr Mn Fe Co Ni Cu Zn Ga Ge Se BrCa Kr
Y Zr Nb Mo Tc Ru Pd Ag Cd In Sn SbSr TeRh
Ba Hf Ta W Re Os Ir Au Hg Tl Pb Bi PoLa AtPt
Ra Rf Db Sg Bh Hs Mt ? ?Ac ?
Al P
N O
S Cl
F Ne
Ar
Rn
I
Si
Xe
B C
As
3
11
19
37
55
87
4
21 22
12
23 24 25 26 27 28 29 30 31 32 34 3520 36
39 40 41 42 43 44 46 47 48 49 50 5138 5245
56 72 73 74 75 76 77 79 80 81 82 83 8457 8578
88 104105106107108109 11111289 110
13 15
7 8
16 17
9 10
18
86
53
14
54
2
5 6
33
Missing elements!
In this periodic table the symbols are replaced by atomic numbers. Some of the numbers are missing – where?
Two more periods of elements fit here but are only shown on some periodic tables. These are called the lanthanides and actinides.
H
Li
Na
K
Rb
Cs
Fr
Be
Sc Ti
Mg
V Cr Mn Fe Co Ni Cu Zn Ga Ge Se BrCa Kr
Y Zr Nb Mo Tc Ru Pd Ag Cd In Sn SbSr TeRh
Ba Hf Ta W Re Os Ir Au Hg Tl Pb Bi PoLa AtPt
Ra Rf Db Sg Bh Hs Mt ? ?Ac ?
Al P
N O
S Cl
F Ne
Ar
Rn
I
Si
Xe
He
B C
As
Periodic table
Stick in book and label groups, periods
1+ ion ProtonsElectrons
1- ion ProtonsElectrons
Ions and Electron Structures
• Ions are atoms that have either extra electrons added or electrons removed.
Atoms ProtonsElectrons
Lose 1 electron Gain 1 electron
So in ions the number of
electrons no longer equals the
number
of protons
Title - Ions
• These are ions formed by the atom losinglosing one or more electrons.
• They are called cationscations. This is because during electrolysis they move towards the cathode. (Or because they are “pussytive”!).
• The charge on the ions is equal to the number of equal to the number of electrons that the atom has lostelectrons that the atom has lost.
• In equations the charge is usually shown above and to the right of the symbol. (E.g. Mg2+ ).
Positive Ions
Lost 1 e- +
Lost 2 e- 2+
Lost 3 e- 3+
It is nearly always metal
atoms that lose
electrons
Ions usually have
OUTER electron
shells that are either completely full or else
empty
Na Bye!
The Electrons in a Sodium IonIn the sodium atomatomAtomic number = number of protons = 11 Number of electrons = 11
Electron arrangement: 2.8.1 (Incomplete Shell)
Na+
Electron lost
Electron arrangement: 2.8 (Full Shells)
23
Na11
Mg
The Electrons in a Magnesium IonIn the magnesium atomatomAtomic number = number of protons = 12 Number of electrons = 12
Electron arrangement = 2.8.2 (Incomplete shell)
Mg2+
Electron arrangement 2.8 (Full Shells)
Bye!
Bye!
2 electrons lost
24
Mg12
The Lithium Ion
Li
3
2
1
1st Shell = 2: full
2nd Shell = 1: not full
2.1
1
•How many electrons?
•How many electrons in the first shell?
•How many electrons in the second shell?
What electron arrangement?
How many electrons to lose?
New electron arrangement? Include a diagram
2.(0)
Bye!Li+
7
Li3
Activity
The Boron Ion
B
5
2
3
1st Shell = 2: full
2nd Shell = 3: not full
2.3
3
•How many electrons?
•How many electrons in the first shell?
•How many electrons in the second shell?
What electron arrangement?
How many electrons to lose?
New electron arrangement? 2.(0)
Bye!
Bye!
Bye!
B3+
11
B5
Activity
• Write/draw a summary of what you now know about positive ions
• Lose or gain electrons?• Go to + or – in electrolysis?• The charge of an ion is less, equal
or more than the number of electrons lost?
• How are they written? • Draw structure of
Mg ion (Mg = 12 electrons)
Lose electron
-, Cations, “pussytive”
Equal
Na+, Mg2+
What have I learnt?
m5
Mg2+
• These are ions formed by the atom gaininggaining one or more electrons.
• They are called anionsanions. This is because during electrolysis they move towards the anode.
• The charge on the ions is equal to the number of equal to the number of electrons that the atom has gainedelectrons that the atom has gained.
• In equations the charge is usually shown above and to the right of the symbol. (E.g.. O2- ).
Negative Ions.
Gain 1 e- -
Gain 2 e- 2-
Gain 3 e- 3-
It is nearly always
non-metal atoms that
gain electrons
Ions usually have
OUTER electron
shells that are either completely full or else
empty
The Electrons in a Sulphide Ion.In the sulphur atomatomAtomic number = number of protons = 16 Number of electrons = 16
Electron arrangement: 2.8.6 (incomplete shell)
Electron arrangement 2.8.8 (Full shells)
2 electrons gained
S S2-
32
S16
The Electrons in a Fluoride Ion.
In the fluorine atomatomAtomic number = number of protons = 9 Number of electrons = 9
Electron arrangement: 2.8.7 (incomplete shell)
Electron arrangement 2.8.8 (Full shells)
1 electron gained
F F-
19
F9
The Oxide Ion16
O8
O
8
2
6
1st Shell = 2: full
2nd Shell = 6: not full
2.6
2
•How many electrons?
•How many electrons in the first shell?
•How many electrons in the second shell?
What electron arrangement?
How many electrons to gain?
New electron arrangement? 2.8
O2-
Activity
• Write/draw a summary of what you now know about negative ions
• Lose or gain electrons?• Go to + or – in electrolysis?• The charge of an ion is less, equal
or more than the number of electrons lost?
• How are they written? • Draw structure of
O ion(O 8 electrons)
Gain electron
+, anions
Equal
Cl-, O2-
What have I learnt?
m5
O2-
x
x
Sodium with Chlorine• Write a word equation for the
reaction• Write a balanced symbol equation• Label equation with group for
elements• Label equation with properties• Draw the sodium and chloride ion
structure
What have I learnt?
The End