C2. The Periodic Table (Y10 - Autumn 1)

Question 1

🟢 What is an Ion?

Answer 1

Ions are particles that contain a different number of protons and electrons and so they are electrically charged.

Question 2

🟢 Why are Ions formed?

Answer 2

Atoms often react to gain or lose electrons. When this happens they gain or lose electrons in order to get stable electron structure of a noble gas. (This means when their outer electron shell is full).

Question 3

🟢 How are Elements arranged in the Periodic Table?

Answer 3

Elements in the Periodic Table are arranged in order of their atomic number, meaning elements can be grouped together in a set of groups and periods, with there being 8 groups and 6 periods.

Question 4

🟢 Why is it called the Periodic Table?

Answer 4

It is called the periodic table because it is a set of repeating patterns, hence the word periodic.

Question 5

🟢 What do elements in the same group have in common?

Answer 5

Elements in the same group in the periodic table have similar characteristics, like their atomic and electronic structure but the further down the periods they go, the more reactive they get. They also have similar melting points, boiling points and e.c.t which also increase further down the group.

Question 6

🟢 Metals react to form…

Answer 6

… Positive Ions (they lose an electron)

Question 7

🟢 Non-metals react to form…

Answer 7

… Negative Ions (they gain an electron)

Question 8

🟢 Why are noble gases unreactive?

Answer 8

Noble gases are unreactive and do not easily form molecules because they already have a full outer shell, meaning they will need to use more energy to gain the necessary amount of sub-atomic particles, making it harder for them to form ions and molecules.

Question 9

🟢 How do the properties change for Group 1 and Group 7 metals as it goes further down the group.

Answer 9

Group 1:

As you go down the group the density increases, the reactivity increases, the melting point increases, the boiling point increases

Group 7:

As you go down the group the density increases, the reactivity decreases, the melting point increases, the boiling point increases

Question 10

🟢 Why does a Halogen form a halide ion and explain the trend in reactivity of halogens as you go down the group

Answer 10

Halogens form halide ions as they will gain an electron in their outer shell. The reactivity will decrease as the group goes down, because as you go down the group the nuclear charge increases, the atomic radius increases and the electron shielding increases, therefore the attraction of the nucleus on the electron decreases.

(With group 1 it would be the opposite to this).

Question 11

🟠 Properties of Transition Metals

Answer 11

Transition Metals Only:

• Compounds are coloured
• They are strong and hard
• They have high densities
• They form different ions
• They are not very reactive
• They have high melting points
• They are useful as catalysts

Transition Metals + Group 1:

• Form ionic compounds on reaction with non-metals
• They are good thermal and electrical conductors

Question 12

🟢 Properties of Group 1 Metals

Answer 12

Group 1 Metals Only:

• Compounds are white
• They are very reactive
• They form +1 ions only
• They have relatively low melting points
• They react with water forming an Alkaline solution and H2 gas
• They are soft and can be cut with a knife
• They are low density and some can float on water

Group 1 + Transition Metals:

• Form ionic compounds on reaction with non-metals
• They are good thermal and electrical conductors

Question 13

🟢 What Are The Diatomic Molecules

Answer 13

• Hydrogen (H 2)
• Nitrogen (N 2)
• Oxygen (O 2)
• Fluorine (F 2)
• Chlorine (Cl 2)
• Bromine (Br 2)
• Iodine (I 2)
• Astatine (At 2)

Question 14

🟢 Halogens that exist as diatomic molecules

Answer 14

• Fluorine (F 2)
• Chlorine (Cl 2)
• Bromine (Br 2)
• Iodine (I 2)
• Astatine (At 2)

Question 15

🟢 What is Covalent Bonding?

Answer 15

A covalent bond forms when two non-metal atoms share a pair of electrons. The electrons involved are in the outer shells of the atoms. An atom that shares one or more of its electrons will complete its outer shell.

Covalent bonds are strong - a lot of energy is needed to break them. Substances with covalent bonds often form molecules with low melting and boiling points, such as hydrogen and water.

Question 16

🟢 What is Ionic Bonding

Answer 16

In ionic bonding, the atoms involved lose or gain electrons to form charged particles called ions. The ions have the electronic structure of a noble gas. So for example, if sodium (2,8,1) from Group 1 loses an electron, it is left with a stable electronic structure of (2,8)

However, it is also left with one more proton in it’s nucleus than the are are electrons around the nucleus. The proton has a positive charge so the sodium atom has now become a positively charged ion. The sodium ion has a single positive charge. The formula of a sodium ion is written as Na^+. The electronic structure of the Na^+ ion is 2,8.

Question 17

🟢 History of the Periodic Table: How many elements were known in 1750?

Answer 17

Only around 10 elements were known in 1750.

Question 18

🟢 History of the Periodic Table: What did Johann Wolfgang Döbereiner discover in 1829?

Answer 18

In 1829, Johann Wolfgang Döbereiner found that there were groups three elements which had similar properties. Relative atomic mass (r.a.m) were being measured at this time and he noticed a curious relationship. The average r.a.m of the first and third elements were equal or close to the r.a.m of the second element. These became known as “Döbereiner Triads”.

Question 19

🟢 History of the Periodic Table: What did John Newlands discover in 1864?

Answer 19

Newlands arranged the 60 known elements known at the time into a table in order of relative atomic mass.

He suggested that starting from a given element, every 8th element has similar properties. In the table, every 8th element starts a new row, so the columns contain elements with similar properties. He called this the “Law of Octaves”.

(This works up to Calcium but but breaks down after this, meaning it was not accepted at the time).

Question 20

🟢 History of the Periodic Table: What did Dmitri Mendeleev discover in 1869?

Answer 20

In 1869, Mendeleev published a periodic table. Like Newlands, he arranged known elements in order of relative atomic mass, but here, he left gaps so that elements with similar chemical and physical properties were in the same vertical groups.

Mendeleev proposed that the gaps corresponded to elements that hadn’t been discovered and he was able to predict the properties they’d have (these elements have been discovered since)

Question 21

🟢 History of the Periodic Table: What did Henry Moseley discover in 1913?

Answer 21

Since Mendeleev’s time, elements had been arranged in relative atomic masses. However, the position predicted by an element’s relative atomic mass did not always match the predicted position.

At the time, what we now call the atomic number was just the position of the element in the table. In 1913 Henry Moseley found a way to measure the number of positive charges in the nucleus (what we now know as the atomic number)

When Moseley arranged the elements in the periodic table by their number of protons rather than their atomic weights, the flaws in the table disappeared (Potassium having a lower Ar than Argon + Iodine having a lower Ar than Tellurium).

Moseley also left gaps like Mendeleev and predicted 4 new elements with 43, 61, 72 and 75 protons.

Question 22

🟢 History of the Periodic Table: Present Day

Answer 22

In the last 100 years, new elements have been discovered to give the complete periodic table that we have at our disposal today.

Elements after Uranium do not occur naturally and are made by bombarding other elements with high energy particles. (These elements in question are radioactive elements).

Question 23

🟢 How does displacement work? (E.g Group 7)

Answer 23

A more reactive halogen can displace a less reactive halogen from solutions of its salts. For example, chlorine is more reactive than iodine. A solution of chlorine can displace iodine from potassium iodide solution.

Question 24

🟢 What happens when chlorine water is added to potassium chloride

Answer 24

Chlorine + Potassium Chloride

No reaction, meaning no displacement, meaning the colour of the solution does not change.

Question 25

🟢 What happens when chlorine water is added to potassium bromide

Answer 25

Bromine + Potassium Chloride

There is a reaction, as the bromine is displaced by the chlorine (as the chlorine is more reactive), forming a yellow solution.

Question 26

🟢 What happens when chlorine water is added to potassium iodide

Answer 26

Iodine + Potassium Chloride

There is a reaction, as the iodine was displaced by the chlorine (as the chlorine is more reactive), forming a dark brown solution.

Question 27

🟢 What happens when bromine water is added to potassium chloride

Answer 27

Bromine + Potassium Chloride

No reaction, meaning no displacement, meaning the colour of the solution does not change.

Question 28

🟢 What happens when bromine water is added to potassium bromide

Answer 28

Bromine + Potassium Bromide

No reaction, meaning no displacement, meaning the colour of the solution does not change.

Question 29

🟢 What happens when bromine water is added to potassium iodide

Answer 29

Iodine + Potassium Bromide

There is a reaction, as the iodine was displaced by the bromine (as the bromine is more reactive), forming a light brown brown solution.

Question 30

🟢 What happens when iodine water is added to potassium chloride

Answer 30

Iodine + Potassium Chloride

No reaction, meaning no displacement, meaning the colour of the solution does not change.

Question 31

🟢 What happens when iodine water is added to potassium bromide

Answer 31

Iodine + Potassium Bromide

No reaction, meaning no displacement, meaning the colour of the solution does not change.

Question 32

🟢 What happens when iodine water is added to potassium iodide

Answer 32

Iodine + Potassium Iodide

No reaction, meaning no displacement, meaning the colour of the solution does not change.

Question 33

🟢 Chlorine’s appearance in water and cyclohexane

Answer 33

Water:
The liquid is a colourless solution as it is just Chlorine and water.

Cyclohexane:
In Cyclohexane, it separates in two different layers. Looks like two colourless layers.

Question 34

🟢 Bromine’s appearance in water and cyclohexane

Answer 34

Water:
The bromine makes a more orange solution

Cyclohexane:
With the Cyclohexane it has a more yellow/orange layer instead

Question 35

🟢 Iodine’s appearance in water and cyclohexane

Answer 35

Water:
The iodine in water makes a red/brown colour in water

Cyclohexane:
In the Cyclohexane, it becomes more pink in a different layer

Question 36

🟢 What happens when Lithium reacts with Oxygen

Answer 36

After the it is exposed to oxygen to long enough, it’s shiny surface starts to get darker. It burns it a red flame, and it produces a white solid (powder).

Lithium + Oxygen —> Lithium Oxide

(4 Li + O2 —> 2 Li2 O)

Question 37

🟢 What happens when Lithium reacts with Chlorine

Answer 37

They burn in chlorine, and then after this, white powder would be created.

Lithium + Chlorine —> Lithium Chloride

(2 Li + Cl2 —>2LiCl)

Question 38

🟢 What happens when Lithium reacts with Water

Answer 38

The Lithium starts smoking and effervescence (bubbling/fizzing) as it starts to dissolves on the surface, meaning it’s density is lower than water’s. The Universal indicates an Alkalai has been formed because it turns purple from green.

Lithium + Water —> Lithium Hydroxide + Hydrogen

(2 Li + 2 H2O —>2LiOH + H2)

Question 39

🟢 What happens when Sodium reacts with Oxygen

Answer 39

After the it is exposed to oxygen to long enough, it’s shiny surface starts to get darker. It burns it a orange/yellow flame, and it produces a white solid (powder).

Sodium + Oxygen —> Sodium Oxide

(4 Na + O2 —> 2 Na2 O)

Question 40

🟢 What happens when Sodium reacts with Chlorine

Answer 40

They burn in chlorine, and then after this, white powder would be created.

Sodium + Chlorine —> Sodium Chloride

(2 Na + Cl2 —>2NaCl)

Question 41

🟢 What happens when Sodium reacts with Water

Answer 41

The sodium also starts smoking and effervescencing as it starts to dissolve, but doesn’t smoke and fizz as much. The indicator has gone a slightly light purple/blue, meaning it is an Alkali.

Sodium + Water —> Sodium Hydroxide + Hydrogen

(2 Na + 2 H2O —>2NaOH + H2)

Question 42

🟢 What happens when Potassium reacts with Oxygen

Answer 42

After the it is exposed to oxygen to long enough, it’s shiny surface starts to get darker. It burns it a lilac flame, and it produces a white solid (powder).

Potassium + Oxygen —> Potassium Oxide

(4 K + O2 —> 2 K2 O)

Question 43

🟢 What happens when Potassium reacts with Chlorine

Answer 43

They burn in chlorine, and then after this, white powder would be created.

Potassium + Chlorine —> Potassium Chloride

(2 K + Cl2 —> 2KCl)

Question 44

🟢 What happens when Potassium reacts with Water

Answer 44

The potassium also goes in with a bang and starts smoking and fizzing a lot and it starts to dissolve, whilst the indicator turns a purple/blue (making an Alkali). Also orange/red spark fly out of it too.

Potassium + Water —> Potassium Hydroxide + Hydrogen

(2 K + 2 H2O —> 2 KOH +H2)

Question 45

🟢 Who Discovered What about the Periodic Table

Answer 45

1829 - Johann Wolfgang Döbereiner
1864 - John Newlands
1869 - Dmitri Mendeleev
1913 - Henry Moseley

Question 46

🟢 What are Physical Changes in Reactions

Answer 46

• Examples include: melting point, boiling point, density, conductivity
• Involves forces of attraction between particles
• No new substance produced

Question 47

🟢 What are Chemical Changes in Reactions

Answer 47

• Examples include: reactions with oxygen, O2 and water H2O
• Involves the transfer/sharing of electrons
• New substance produced