The Periodic Table

Question 1

How did mendeleev arrange the elements

Answer 1

By their increasing relative atomic mass

Question 2

Why did Mendeleev sometimes move the elements around

Answer 2

If it better suited their chemical properties

Question 3

Why did he leave gaps in the periodic table

Answer 3

He assumed that their would be more elements discovered in the future

Question 4

How many elements were discovered in 1869

Answer 4

63

Question 5

Differences between mendeleeves periodic table and the modern day one

Answer 5

2 elements in one box, no noble gasses discovered

Question 6

Relative atomic mass:

Answer 6

Mean atomic mass of an atom of an element

Question 7

How to calculate the relative atomic mass of an atom

Answer 7

Number of protons plus neutrons

Question 8

How to calculate the number of neutrons

Answer 8

Relative atomic mass take away the atomic number

Question 9

Mass number:

Answer 9

The mass of an atom (protons plus neutrons)

Question 10

Relative atomic mass

Answer 10

The mean mass of an atom taking into account the mass of the isotopes

Question 11

Atomic number

Answer 11

The number of protons and neutrons in an ion

Question 12

What is an isotope

Answer 12

Isotopes are atoms of an element with the same number of protons (and electrons) but different numbers of neutrons. This means their mass numbers will be different

Question 13

3 isotopes of hydrogen

Answer 13

Tritium, deuterium, protium

Question 14

What is an isotope

Answer 14

Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons.

Question 15

Metals in groups 1 and 2 become more reactive as you go down the group.
Explain
why.

Answer 15

The number of shells increases.
This makes it easier to lose an electron.

Question 16

What was the English physicist called who discovered electrons in 1897?

Answer 16

J.J Thompson

Question 17

What was the name of the atomic model devised by J.J. Thomson?

Answer 17

The plum pudding model

Question 18

What did Rutherford discover and what was his model called?

Answer 18

Rutherford discovered that alpha particles could bounce back off atoms

Rutherford discovered that an atom’s mass is concentrated in the atom’s centre.

Rutherford called the atom’s centre the nucleus

Rutherford discovered that the nucleus contained positively charged particles called protons.

Rutherford’s model was called the nuclear model.

Question 19

What do elements in the same groups share

Answer 19

Elements in the same column have the same number of electrons in their outer shell (the highest energy level).

Question 20

What is the relative mass of a proton?

Answer 20

0.0005

Question 21

Which group of elements form DIATOMIC MOLECULES and become LESS REACTIVE as you move down the group?

Answer 21

Group 7

Question 22

What happens when an alkali metal reacts with water?

Answer 22

The metal floats on the surface
Enough energy is created to melt the metal