Period 3 Groups 2 and 17 Elements 1

1. Period 3, Group 2 and Group 17 Elements

Saturday, 28 March 2026
Period 3, Group 2 and
Group 17 Elements
REVISION

2.

Period 3 Elements
Saturday, 28 March 2026

3. Atomic Radii

Saturday, 28 March 2026
Atomic Radii
There is an increased nuclear
charge as there is an increasing
number of protons.
Mg
Al
Si
P
S
Cl
This pulls the outer shell of
electrons further in towards
the nucleus.
Period 3 Atomic Radius
Atomic Radius / nm
As we go across period 3 the atomic
radius decreases
Na
Crucially the extra
electrons elements
gain across the
period go into the
same shell. The
shielding effect is
similar.
0,18
0,16
0,14
0,12
0,1
0,08
0,06
0,04
0,02
0
Na
Mg
Al
Si
P
Period 3 elements
S
Cl

4. Melting Points

Saturday, 28 March 2026
Melting Points
e-
e+
+
e-
ee-
e-
e-
e-
+
e-
+
e-
+
+
+
e-
e-
e+
+
e-
e-
e-
e-
e+
+
+
e-
+
e-
e-
e-
+
e-
First 3 elements (Na, Mg and Al) in period
3 are Metals. They have metallic bonding.
Metallic Structure
for Sodium
+
Period 3 Melting Points
e-
e-ee- - ee- - e- e- - e- e 2+
2+
2+ e 2+ e 2+ e
2+
e-e-
2+
e- e-
e- e- e- e2+
e- e-
2+
e
- e-
e-e- e-e
2+
e- e-
e-
1600
Metallic Structure
for Magnesium
e2+
2+
2+
2+
2+ ee e e e e e e e e e e-
General increase in melting points as metal
ions have an increasing positive charge,
increasing number of delocalised electrons
and smaller ionic radius. This means a stronger
metallic bond.
1400
Temperature / K
e-e- e- e-
1800
1200
1000
800
600
400
200
0
Na
Mg
Al
Si
P
Period 3 elements
S
Cl
Ar

5. Melting Points

Saturday, 28 March 2026
Melting Points
Silicon has the highest melting point in period 3. It has a
giant covalent (macromolecular) structure.
Period 3 Melting Points
1800
1600
Many, strong covalent bonds hold the silicon
atoms together. A large amount of energy is
needed to overcome these strong covalent
bonds.
Temperature / K
1400
1200
1000
800
600
400
200
0
Na
Mg
Al
Si
P
Period 3 elements
S
Cl
Ar

6. Melting Points

Saturday, 28 March 2026
Melting Points
Phosphorus has the formula P4. It has a lower melting point than Silicon due to a weaker
simple molecular structure. Melting point is determined by weaker van der waals forces.
Period 3 Melting Points
1800
1600
Sulfur has the formula
S8. It has a higher
melting point than
Phosphorus due to a
larger simple
molecular structure. It
has larger van der
waals forces and hence
a higher melting point.
Temperature / K
1400
1200
1000
800
600
400
200
0
Na
Mg
Al
Si
P
Period 3 elements
S
Cl
Ar

7. Melting Points

Saturday, 28 March 2026
Melting Points
Chlorine has the formula Cl2. It
has a lower melting point than
Phosphorus & Sulfur due to a
smaller simple molecular
structure. It has smaller van
der waals forces and hence a
lower melting point.
Period 3 Melting Points
1800
1600
1400
Temperature / K
Argon has the formula Ar. It
has a lower melting point than
the rest of the elements in
period 3 due to it only existing
as individual atoms. It has
smaller van der waals forces
and hence a lower melting
point.
1200
1000
800
600
400
200
0
Na
Mg
Al
Si
P
Period 3 elements
S
Cl
Ar

8. Ionisation

Saturday, 28 March 2026
+
Ionisation
Ionisation energy is the minimum amount of energy required to remove 1 mole of electrons from 1 mole of
atoms in the gaseous state
Na(g) Na+(g) +e- 1st IE energy = + 495.8kJmol-1
Always include
state symbols (g)
+
Shielding
The more electrons shells
between the positive nucleus and
negative electron that is being
removed the less energy is
required. There is a weaker
attraction.
Nuclear Charge
The more protons in the nucleus
the bigger the attraction between
nucleus and outer electrons. This
means more energy required to
remove the electron.
+
Ionisation requires energy so they are always an
endothermic processes and have a positive value
Atomic Size
The bigger the atom the further
away the outer electrons are from
the nucleus. The attractive force
between nucleus and outer
electrons reduces – easier to
remove electrons.

9. Successive Ionisation

Saturday, 28 March 2026
+
Successive Ionisation
The removal of more than 1 electron from the same atom is called successive ionisation
Mg+(g) Mg2+(g) +e- 2nd IE energy = + 1450kJmol-1
Energy
3p
↑↓
↑↓ ↑↓ ↑↓
↑↓
↑↓
1s
3s
2p
2s
Jump in energy as removing
electrons from shell closer to
nucleus
Successive ionisation - Mg
Log Ionisation energy kJmol-1
General increase in energy as
removing an electron from an
increasingly more positive ion.
6
5
4
We know this is
Mg as we are
removing 12
electrons.
3
2
1
0
1
2
3
4
5
6
7
8
9
Number of electrons removed
10
11
12

10. 1st Ionisation Trends - Groups

Saturday, 28 March 2026
+
1st Ionisation Trends - Groups
Ionisation energy decreases as we go down a group
The atomic radius increases as we go down the
group. Outer electrons further from the
nucleus. Attractive force is weaker. Energy
required to remove an electron decreases.
This data provides strong evidence for shells in
atoms and proves Niels Bohr’s model of the
atom is correct. BUT it didn’t explain data
shown going across a period. (See next slides)
1000
1st Ionisation energy kJmol-1
Shielding increases as we go down the group.
More shells between nucleus and outer shell.
Attractive force is weaker. Energy required to
remove an electron decreases.
1st ionisation energy in Group 2
900
800
700
600
500
400
300
200
100
0
Be
Mg
Ca
Group 2 elements
Sr
Ba

11. 1st Ionisation Trends – Periods

Saturday, 28 March 2026
+
1st Ionisation Trends – Periods
Ionisation energy increases as we go across a period
Shielding is similar and
distance from nucleus
marginally decreases.
More energy required to
remove an outer electron.
Ionisation energy increases.
1600
1st Ionisation energy kJmol-1
As we go across the period there
is an increasing number of
protons in the nucleus. This
increases the nuclear attraction.
1st ionisation energies in period 3
1400
1200
1000
800
600
400
200
0
Na
Mg
Al
Si
P
Period 3 elements
S
Cl
Ar

12. 1st Ionisation Trends – Periods

Saturday, 28 March 2026
+
1st Ionisation Trends – Periods
A decrease at Aluminium is evidence for atoms having sub-shells
Mg – 1s2,2s2,2p6,3s2
Al - 1s2,2s2,2p6,3s2,3p1
Magnesium
has it’s outer
electron in 3s
sub-shell
The atomic model Niels
Bohr came up with didn’t
explain sub-shells.
Aluminium
has it’s outer
electron in 3p
sub-shell
1600
1st Ionisation energy kJmol-1
The outer most electron in Aluminium
sits in a higher energy sub-shell slightly
further from the nucleus than the outer
electron in Magnesium.
1st ionisation energies in period 3
1400
1200
1000
800
600
400
200
0
Na
Mg
Al
Si
P
Period 3 elements
S
Cl
Ar

13. 1st Ionisation Trends – Periods

Saturday, 28 March 2026
+
1st Ionisation Trends – Periods
A decrease at Sulfur is evidence for electron repulsion in an orbital
Removing an electron from
Sulfur involves taking it from
an orbital with 2 electrons in.
Phosphorous and Sulfur both have
outer electrons in the 3p orbital so
the shielding is the same.
1600
↑↓ ↑
↑
↑↓
Electrons
each
other
↑↓repel
↑↓
↑↓
so less energy is needed2p
to
remove an electron
↑↓ from an
2s
orbital with 2 in than a one
↑↓
with 1 in like
1s Phosphorus.
1st Ionisation energy kJmol-1
Electron Energy
Diagram for Sulfur
Energy
1st ionisation energies in period 3
3p
3s
↑
↑
↑
↑↓
1400
1200
1000
800
600
400
200
3p
0
Na
Mg
Al
Si
P
Period 3 elements
3s
S
Cl
Ar

14.

Group 2 Elements
Saturday, 28 March 2026

15. Atomic Radius

Saturday, 28 March 2026
Atomic Radius
Group 2 elements form +2 ions when they react.
Group 2 metals lose 2 electrons to form +2
ions. All group 2 metals have electron
configurations that end in s2.
Atomic Radius
Be2+ - 1s2
Mg – 1s2, 2s2, 2p6, 3s2
Mg2+ - 1s2, 2s2, 2p6
Ca – 1s2, 2s2, 2p6, 3s2, 3p6, 4s2 Ca2+ - 1s2, 2s2, 2p6, 3s2, 3p6
Extra shells added as
we go down group 2
0,25
0,2
Radius (nm)
Be – 1s2, 2s2
The atomic radius
increases as we go
down group 2.
0,15
0,1
0,05
0
Be
Mg
Ca
Sr
Ba

16. Ionisation Energy

Saturday, 28 March 2026
Ionisation Energy
1st ionisation energy decreases as we go down group 2
The outer electrons are
also further from the
nucleus which weakens
the attraction.
Both of these make
it easier to remove
the outer electron
and so less energy is
needed to remove
the outer electron.
1st ionisation energy
1000
900
800
700
Energy (kJmol-1)
Extra shells added as
we go down group 2
There is more
shielding hence
weaker attraction
between the nucleus
and outer electrons.
600
500
400
300
200
100
We do have an increase in
the number of protons as
we go down the group.
However the shielding
effect overrides an
increase in positive charge.
0
Be
Mg
Ca
Sr
Ba

17. Melting Points

Saturday, 28 March 2026
Melting Points
Melting points generally decrease as we go down the group
Larger ions means the
distance between the
positive nuclei in metal ions
and delocalised electrons is
greater. This weakens the
attractive force.
As we go down the group
the size of the metal ion
increases but the number
of delocalised electrons
remains the same. The
charge (+2) remains the
same too.
This makes it easier
to break bonds and
hence less energy
required. This leads
to lower melting
points.
Melting Point
1400
1200
1000
Temperature (°C)
Group 2 elements form
metallic structures
where you have positive
metal ions attracted to a
delocalised negative sea
of electrons.
800
600
400
200
Magnesium is an exception
due to a structural
difference compared to the
other group 2 metals.
0
Be
Mg
Ca
Sr
Ba

18. Reaction with water

Saturday, 28 March 2026
Reaction with water
Group 2 elements react with water to form bases
Reaction with water to form metal hydroxides
Sr(s) + 2H2O(l) Sr(OH)2(aq) + H2(g)
Be
Mg
Ca
Sr
Ba
Reactivity
increases with
water. (There is no
reaction with Be)
Atom gets larger and
electron is further
from nucleus. Easier
to remove and hence
more reactive. There
is more shielding.
Mg reacts slowly
with cold water
but more
vigorously with
steam. This
produces
Magnesium Oxide
(MgO) instead of a
hydroxide.

19. Group 2 Compounds - Solubility

Saturday, 28 March 2026
Group 2 Compounds - Solubility
Group 2 hydroxides and sulfates have opposite solubility as we go down the group.
As a general rule if the anion (negative ion)
has a double charge they become less
soluble as we go down the group.
Generally, if the anion (negative ion) has a
single charge they become more soluble as
we go down the group.
Element
Sulfates (SO42-)
Hydroxide (OH-)
Magnesium
Very Soluble
Sparingly Soluble
Calcium
Fairly Soluble
Slightly Soluble
Strontium
Slightly Soluble
Fairly Soluble
Barium
Sparingly Soluble
Very Soluble

20. Tests for sulfates

Saturday, 28 March 2026
Tests for sulfates
Test for sulfates using Barium Chloride
To see if a compound
contains sulfate ions just add
the following1. Add hydrochloric acid
(HCl) to remove any
carbonates in. These could
precipitate out after
adding barium chloride
giving a false result.
2. Add barium chloride
Testing for
Sulfates
Barium
Sulfate
precipitate
You will observe a white precipitate if there are sulfates.
The white precipitate is barium sulfate – this is insoluble.
Ba2+(aq) + SO42-(aq) BaSO4(s)
BaCl2(aq) + ZnSO4(aq) BaSO4(s) + ZnCl2(aq)

21. Neutralisation

Saturday, 28 March 2026
Neutralisation
Group 2 compounds can be used to neutralise acids
Acidic Soils
Antacids
Calcium Hydroxide – Ca(OH)2
(slaked lime) is used to
neutralise acidic soils
Magnesium Hydroxide –
Mg(OH)2 is used to neutralise
excess stomach acid.
The ionic equation for
neutralisation isH+(aq) + OH-(aq) H2O(l)
Source - CSIRO

22. Barium Meals

Saturday, 28 March 2026
Barium Meals
Barium Sulfate is also known as a ‘Barium meal’
Barium Sulfate is used to help
identify problems with the
digestive tract.
Source – Lucien Monfils
https://commons.wikimedia.org/wiki/File:Maag.jpg
The patient stands in an x-ray
machine. X-rays are absorbed
by barium sulfate so will show
up on an x-ray. Normally soft
tissues won’t show up as xrays go straight through.
A patient drinks
a suspension of
barium sulfate.
This coats the
lining of soft
tissues such as
the stomach.
Barium compounds are toxic –
however because barium
sulfate is insoluble it can’t be
absorbed into the blood.

23. Extraction of Titanium

Saturday, 28 March 2026
Extraction of Titanium
Magnesium is used to extract titanium from it’s ore (rutile)
1. Titanium ore (TiO2) is
converted to
titanium(IV)chloride (TiCl4) by
heating with carbon and
chlorine gas.
2. The titanium(IV)chloride
produced in step 1 is passed
through a fractional
distillation column to increase
the purity.
Titanium is light
weight but strong
and is commonly
used in planes.
Source – Cory W. Watts
https://commons.wikimedia.org/wiki/File:Titanium!!_(6617764885).jpg
3. The purified
TiCl4 is reduced
using
magnesium in
1000°C furnace.
TiCl4 + 2Mg Ti + 2MgCl2

24. Removal of Sulfur Dioxide

Saturday, 28 March 2026
Removal of Sulfur Dioxide
Use calcium carbonate and oxide to remove sulfur dioxide emissions
Electricity can be produced by
burning fossil fuels like coal.
This produces sulfur dioxide
gas which is a pollutant.
A process called wet scrubbing
is a method whereby an alkali
is used to neutralise sulphur
dioxide in flue gases.
The product of this reaction is calcium sulfite which
can be used in the production of plasterboard.
CaCO3(s) + 2H2O(l) + SO2(g) CaSO3(s) + 2H2O(l) + CO2(g)
CaO(s) + 2H2O(l) + SO2(g) CaSO3(s) + 2H2O(l)
Wet scrubbing
involves dissolving
calcium carbonate or
oxide in water and
spraying on acidic
sulphur dioxide gas.

25.

Group 17 Elements
Saturday, 28 March 2026

26. The Halogens

Saturday, 28 March 2026
The Halogens
The halogens make up group 17 or 7A of the periodic table
Fluorine F2
PALE YELLOW GAS
1s2, 2s2, 2p5
Chlorine Cl2
PALE GREEN GAS
1s2, 2s2, 2p6, 3s2, 3p5
Bromine Br2
BROWN-ORANGE LIQUID
1s2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s2, 4p5
Iodine I2
GREY SOLID
1s2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s2, 4p6,
4d10, 5s2, 5p5
BOILING POINTS
This increases as we go down the group. This is because the van der
waals forces increase due to the increasing size and relative mass of
the atoms.
The physical state goes from gas at the top of group 7 to solid at the
bottom.
ELECTRONEGATIVITY
This decreases as we go down the group. Electronegativity is the ability
for an atom to attract electrons towards itself in a covalent bond. The
atoms get larger and the distance between the positive nucleus and
bonding electrons increases. There is also more shielding.

27. Displacement Reactions

Saturday, 28 March 2026
Displacement Reactions
More reactive halogens will displace less reactive halide ions
Reactivity in halogens decreases as we go down group 7.
For a reaction to occur an electron is gained. Atoms with a
smaller radius attract electrons better than larger atoms.
Halogens are less oxidising as we go down the group. We
can show this by reacting halogens with halide ions.
A HALOGEN WILL DISPLACE A HALIDE FROM SOLUTION IF
THE HALIDE IS LOWER IN THE PERIODIC TABLE
Potassium chloride solution
(KCl) – colourless
Potassium bromide solution
(KBr) – colourless
Potassium iodide solution
(KI) – colourless
Addition of chlorine water
(Cl2) – almost colourless
No reaction
Orange solution (Br2) made
Cl2 + 2Br- 2Cl- + Br2
Brown solution (I2) made
Cl2 + 2I- 2Cl- + I2
Addition of bromine water
(Br2) - orange
No reaction
No reaction
Brown solution (I2) made
Br2 + 2I- 2Br- + I2
Addition of iodine solution
(I2) - brown
No reaction
No reaction
No reaction

28. Bleach

Saturday, 28 March 2026
Bleach
Bleach is made via a disproportionation reaction
Mixing chlorine and sodium hydroxide will form
sodium chlorate(I) solution – also known as bleach.
2NaOH(aq) + Cl2(g) NaClO(aq) + NaCl(aq) + H2O(l)
Uses of sodium chlorate(I)
- Treating water
- Bleaching paper and fabrics
- Cleaning agents (bleach)
Has an
oxidation
state of 0
Has an
oxidation
state of +1
Has an
oxidation
state of -1
Chlorine has been
simultaneously
reduced and
oxidised. We call this
a disproportionation
reaction.

29. Water Sterilisation

Saturday, 28 March 2026
Water Sterilisation
Adding chlorine to water can kill bacteria in water
Adding water to chlorine will produce chlorate(I) ions (ClO-) which kill bacteria. Useful in
drinking water and pools.
Chlorine has been
simultaneously reduced
and oxidised. We call
this a
disproportionation
reaction.
H2O(l) + Cl2(g) 2H+(aq) + Cl-(aq) + ClO-(aq)
Has an
oxidation
state of 0
Has an
oxidation
state of -1
2H2O(l) + Cl2(g) 4H+(aq) + 2Cl-(aq) + O2(g)
Has an
oxidation
state of +1
Sunlight can decompose
chlorinated water too.
However NO ClO- is made.

30. Drinking Water

Saturday, 28 March 2026
Drinking Water
There are advantages and disadvantages of chlorinating drinking water
Advantages
Disadvantages
Destroys microorganisms that cause
disease
Chlorine gas is toxic and irritates the
respiratory system.
Long lasting so reduces bacteria build
up further down the supply.
Liquid chlorine causes severe
chemical burns to the skin.
Reduces the growth of algae that
discolours water and can give it a bad
smell and taste.
Chlorine can react with organic compounds
present in the water to make chloroalkanes.
These have been linked with causing cancer.
However the risk of not chlorinating water
could lead to a cholera epidemic.

31. Reducing Power of Halide Ions

Saturday, 28 March 2026
Reducing Power of Halide Ions
Halide ions lose an electron in reactions and so they are reducing agents
F-
ClBr-
I-
As we go down the group the ionic
radius increases.
The distance between the nucleus and
outer electrons becomes larger and
there is more shielding. The attractive
force gets weaker.
The outer electron is lost more readily
and this is the reason why I- is a more
powerful reducing agent than F-
There are 2 tests to
prove this trend –
1. Reaction with
sulfuric acid
2. Reaction with silver
nitrate solution
(see next slides)

32. Halide ions with sulfuric acid

Saturday, 28 March 2026
Halide ions with sulfuric acid
Some halide ions can reduce concentrated sulfuric acid
NaHSO4
+6
Cl-
A
Br-
A
I-
SO2
+4
S
0
H2S
-2
Reduction products
A
B
B
Point A (Not redox reaction)
Orange vapour
of Br2 produced
D
C
White misty
fumes produced
With NaCl - H2SO4 + NaCl NaHSO4 + HCl
Yellow solid
With NaBr - H2SO4 + NaBr NaHSO4 + HBr
of S produced
With NaI - H2SO4 + NaI NaHSO4 + HI
Rotten egg smell
CLICK HERE TO SEE A FURTHER
of H2S produced
EXPLANATION IN VIDEO FORM
Point B (in addition to A)
With NaBr (Same reaction with NaI) –
2Br- Br2 + 2e- (Br- ions oxidised)
H2SO4 + 2H+ + 2e- SO2 + 2H2O (S being reduced)
Overall ionic - H2SO4 + 2H+ + 2Br- Br2 + SO2 + 2H2O
Point C (in addition to A&B)
With NaI –
6I- 3I2 + 6e- (I- ions oxidised) ×3 to get 6eH2SO4 + 6H+ + 6e- S + 4H2O (S being reduced)
Overall ionic - H2SO4 + 6H+ + 6I- 3I2 + S + 4H2O
Point D (in addition to A,B&C)
With NaI –
8I- 4I2 + 8e- (I- ions oxidised) ×4 to get 8eH2SO4 + 8H+ + 8e- H2S + 4H2O (S being reduced)
Overall ionic - H2SO4 + 8H+ + 8I- 4I2 + H2S + 4H2O

33. Halide ions with silver nitrate

Saturday, 28 March 2026
Halide ions with silver nitrate
Test for halides using silver nitrate then confirm with ammonia solution
Testing for Chloride (Cl-), Bromide (Br-) and Iodide (I-) just involves adding dilute nitric acid (HNO3) then silver nitrate
solution (AgNO3). The colour of the precipitate will help you identify the halide ion.
Iodide ions
Yellow precipitate forms (silver iodide)
Ag+(aq) + I-(aq) AgI(s)
Chloride ions
White precipitate forms (silver chloride)
Ag+(aq) + Cl-(aq) AgCl(s)
Bromide ions
Cream precipitate forms (silver bromide)
Ag+(aq) + Br-(aq) AgBr(s)
FURTHER TEST – add AMMONIA (NH3)
solution to precipitates
Cl- white precipitate dissolves in
dilute NH3
Br- cream precipitate dissolves in
concentrated NH3
I- yellow precipitate insoluble in
concentrated NH3
We add nitric acid to react with any
anions other than halides (e.g.
Carbonates). This could give a false
result otherwise.
Cychr - https://en.wikipedia.org/wiki/File:Common_Silver_Halide_Precipitates.jpg#filelinks

34. Tests for ions

Saturday, 28 March 2026
Tests for ions
Test for group 2 ions (cations) in a compound using flame tests
1. Dip the nichrome wire in concentrated
hydrochloric acid
2. Dip into sample
3. Place the loop into the BLUE Bunsen flame
and observe the colour
DARK RED - Calcium Ca2+
RED - Strontium Sr2+
GREEN - Barium Ba2+
Flame tests
These are used to identify group 2
ions in a solid sample. They can be
made into solutions and sprayed on
the Bunsen too, however this may be
difficult if the sample being tested is
insoluble.

35. Tests for ions

Saturday, 28 March 2026
Tests for ions
Test for ammonium compounds and hydroxides using Litmus paper
Testing for Ammonium Compounds
Add sodium
hydroxide (NaOH),
gently heat, and if
ammonium
compound present
ammonia gas will
be produced.
NH4+(aq) + OH-(aq) NH3(g) + H2O(l)
Use damp red
litmus. Ammonia
will dissolve in the
water and turn
litmus blue.
Testing for Hydroxides
Hydroxides are alkaline and they will turn red litmus
blue.
This test doesn’t mean you will definitely have
hydroxides. Red litmus turns blue for any alkali.
Further tests are needed to confirm you have an alkali.

36. Tests for ions

Saturday, 28 March 2026
Tests for ions
Test for carbonates and sulfates using Hydrochloric Acid and Barium Chloride
Testing for Carbonates
CO32- + 2H+ CO2 + H2O
Hydrochloric
acid reacts with
Carbonates to
make CO2 gas.
When bubbled
through
limewater it
turns cloudy.
Testing for Sulfates
To see if a compound contains sulfate
ions just add the following1. Add hydrochloric acid (HCl) to
remove any carbonates in. These
could precipitate out after adding
barium chloride giving a false result.
2. Add barium chloride
Barium
Sulfate
precipitate?
You will observe a white precipitate if there are sulfates.
The white precipitate is barium sulfate – this is insoluble.
Ba2+(aq) + SO42-(aq) BaSO4(s)

37. Tests for ions

Saturday, 28 March 2026
Tests for ions
Test ions in a specific order to prevent false positives.
NO?
Carbon Dioxide
gas produced?
Test for halides
Test for sulfates
Test for carbonates
Barium Sulfate
precipitate?
NO?
Cychr https://en.wikipedia.org/wiki/File:Common_Silver_Halide_Precipi
tates.jpg#filelinks
Look out for white, cream and
yellow precipitates