The periodic table, Ions (tests, compounds, precipitates)

Question 1

The atomic number is also the same as the _______ number.

Answer 1

Proton.

Question 2

The atomic mass is _______ + ________.

Answer 2

Protons + Neutrons.

Question 3

What is meant by atomic mass?

Answer 3

The mass in relation to carbon-12.

Question 4

True or false:

The pre-mendelev periodic table had gaps.

Answer 4

False.

Question 5

What do the groups in the periodic table represent?

Answer 5

Number of electrons on the outermost shell and that the elements have similar chemical properties.

Question 6

What do the periods represent?

Answer 6

The number of electron shells an element has.

Question 7

What is an isotope?

Answer 7

Same number of protons but a different number of neutrons.

Question 8

Name 4 characteristics of the pre-mendelev periodic table.

Answer 8

1. There were no gaps (they assumed they found all the elements).
2. The elements were ordered in terms of mass.
3. There were not many elements.
4. Chemical properties were not considered.

Question 9

What are the differences between the pre-mendelev table and the modern one?

Answer 9

• Elements on the MPT where arranged in the order of RAM and not of mass.
• Properties were considered in the MTP but not on the pre-mendelev table.
• Mendelev left gaps for other elements that hadn’t been discovered yet but the pre-mendelev one had no gaps.

Question 10

What is meant by an ion?

Answer 10

An atom with a charge.

Question 11

What are cations?

Answer 11

Positively charged atoms.

Question 12

What are anions?

Answer 12

Negatively charges ions.

Question 13

Metal atoms lose electrons to form ______.

Answer 13

Cations.

Question 14

Non-metal atoms gain electrons to form______.

Answer 14

Anions.

Question 15

When a compound ends in ‘-ate’ what can this tell you?

Answer 15

That oxygen is part of the compound.

Question 16

Name 4 properties of ionic compounds.

Answer 16

1. High melting points.
2. High boiling points.
3. They are soluble.
4. Can conduct electricity when molten or aqeous only.

Question 17

All common salts of _____, ________, and _________ are soluble in water.

Answer 17

(Remember: SPA)

Sodium, potassium and ammonium.

Question 18

What 2 chlorides cannot dissolve in water?

Answer 18

(Remember: Sledge hammer)

Silver and lead.

Question 19

What 3 sulfates cannot dissolve in water?

Answer 19

(Remember: LBC 97.3 or PbBaCa)

Lead, Barium and calcium.

Question 20

Most __________ and ___________ are insoluble in water (with the exceptions of SPA).

Answer 20

Carbonates, hydroxides.

Question 21

How would you prepare a salt from 2 solutions? (4)

Answer 21

• Mix the 2 solutions.
• Filter the mixture.
• Wash the insoluble salt with water.
• Leave to dry.

Question 22

Why is barium sulfate safe to swallow even though it’s toxic?

Answer 22

It’s insoluble, so it will not dissolve into the blood and cause harm.

Question 23

Name the colour of the flame for the following ions:

1. Sodium
2. Postassium
3. Calcium
4. Copper

Answer 23

1. Yellow
2. Lilac
3. Brick red
4. Green-blue

Question 24

How would you test for carbonate ions?

Answer 24

1. Add dilute acid to the substance.
2. Test the gas given off using limewater.

If the substance contains carbonate ions:

• It will fizz or bubble as the gas is given off.
• It would turn the limewater cloudy showing the gas is carbon dioxide.

Question 25

How would you test for sulfate ions?

Answer 25

1. Add a few drops of dilute HCl.
2. Shake the mixture.
3. Add a few drops of barium chloride to the solution.

If the substance contains sulfate ions a white precipitate of barium sulfate will form.

Question 26

How would you test for chloride ions?

Answer 26

1. Add a few drops of nitric acid.
2. Shake the mixture.
3. Add a few drops of silver nitrate to the solution.

If the substance contains chloride ions a white precipitate of silver chloride forms.

Question 27

Why do ionic substances have high melting and boiling points? (3)

Answer 27

• There are strong electrostatic forces between the particles are the ionic bonds.
• It takes a lot of energy for these bonds to be broken.