Chapter 30 - The Periodic Table

Question 1

Why is the periodic table so called?

Answer 1

The properties of the elements repeat at various intervals, e.g. the properties of lithium (3) are repeated in sodium (11) and potassium (19)

Question 2

What is the definition of the periodic table?

When was it first drawn up and by whom?

Answer 2

The periodic table is an arrangements elements in order of increasing atomic number
In 1869 by a Russian chemist called Dmitri Mendeleev

Question 3

What are the vertical columns of elements with similar properties called, and how many main ones are there?

Answer 3

Groups/families, and eight

Question 4

What is the group on the extreme right called?

Answer 4

Group VIII/ Group 0 - the groups are often numbered using old Roman numerals

Question 5

What are some things all elements in the same group have in common?

Answer 5

• similar chemical properties
• same number of electrons in their outer orbit/shell (it’s these electrons that determine the chemical properties of the elements)

Question 6

Name group I, group II, group VIII, and group 0

Answer 6

Alkali metals, alkaline earth metals, (transition metals), halogens, noble (inert) gases

Question 7

What are the horizontal rows of elements called? Say 4 things about them.

Answer 7

Periods

• there are 7 periods in the periodic table
• the first one contains only hydrogen and helium
• the second one contains the elements from lithium to neon
• they’re usually labelled n = 1, n = 2 etc.

Question 8

To draw the Bohr structure of an atom what do you need to be able to do?

Answer 8

1. Use the periodic table to work out the number of protons and neutrons in the nucleus of the atom
2. Use the periodic table to show the arrangement of electrons in the atom

Question 9

How is the way atomic/mass numbers are presented in the periodic table different to how they’re presented in a nuclear formula?

Answer 9

The numbers are the other way around - the atomic number is on top, and the mass number is on the bottom. Just remember that the atomic number is always the smaller number, and so when organising the periodic table they put it on top so the mass number could carry it using its mass.

Question 10

How do you find the mass number of an element by looking at the periodic table?

Answer 10

Round the number under the symbol to the nearest whole number

Question 11

What should you do when drawing a Bohr structure? Use carbon as an example :)

Answer 11

• write the number of protons and neutrons next to the nucleus ( 6p, 6n)
• write the nuclear formula (^12^6C) and electron configuration under the diagram (2,4)

Question 12

What are Isotopes?

Answer 12

Isotopes are atoms of the same element that have different numbers of neutrons
In other words, they have the same atomic number but different mass numbers
Comparable to Easter eggs; a company makes an egg with red and green sweets in the centre, but there are two varieties, one with 10 of each and one with 10 red and 15 green, making it heavier

Question 13

Give an example of an element with isotopes, and a special use of one of them

Answer 13

Carbon has 3 isotopes, the mass numbers of which are 12, 13 and 14
Carbon-14 is used by scientists to figure out how old something is by seeing how much of it there is in the substance (carbon dating)