Chapter 2 : The Periodic Table Flashcards Preview

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Flashcards in Chapter 2 : The Periodic Table Deck (18):
1

How many known elements are there?

118

2

What are the elements beyond uranium?

Radioactive
Transuranium
Not naturally occurring

3

Dmitri Mendeleev Periodic table

He created the first table
He arranged the table in order of increasing atomic size
He grouped the elements

4

Groups on the periodic table

Group 1 - Alkali earth
Group 2 - Alkaline earth
Group 3-12 - Transition metals
Group 17 - Halogens
Group 18 - Noble gases
Bottom rows - Lanthanoids and actinoids

5

Periods

Horizontal rows
Corresponds to the number of shells

6

Groups

Vertical columns
Corresponds the number of outer electrons

7

Blocks of elements in the periodic table

S block - Group 1 and 2 and helium
D block - Group 3-12
P block - Group 13-18
F block - lanthanoids and actinoids

8

General properties of metals

High melting/boiling points
Good conductors of heat/electricity
Opaque
Shiny
Ductile/Malleable
Strong
Form positive ions

9

General properties of non-metals

Low melting/boiling points
Poor conductors of heat/electricity
Transparent in a thin sheet
Dull
Brittle when solid
Weak
Form negative ions

10

Atomic size

It increases going down because the further down you go in a group the more shells are added and therefore becoming larger, the inner electrons create a shielding effect
It decreases going across as no new shells are added but the nuclear charge increases and pulls the electrons closer

11

Ionisation energy

The energy required to remove an electron from an atom in its gaseous state
It decreases going down the group because the valence electrons are further away from the nucleus and not as strongly held therefore a lower ionisation energy
It increases going across the period as the nuclear charge is increasing but the shielding effect is the same, the electrons are held stronger to the nucleus and therefore a higher ionisation energy

12

Electronegativity

The measure of the degree in which an atom can attract an electron to itself
Fluorine is the most electronegative element
It increases as it moves across a period as the nuclear charge increases and the more protons the greater the electron-attracting power
It decreases down a group because the outer electrons are further away from the nucleus and shielding effect decreases the electron-attracting power

13

Metallic characteristics

Determined by its ease in losing electrons
They lose metallic character going across a period as the increasing nuclear charge holds them close to the nucleus making it harder to separate
They increase metallic character going down a group as the outer shell electrons are further away from the nucleus and easier to lose

14

Oxidising strength

How readily an element gains electrons
An oxidant causes oxidisation by gaining electrons but is itself reduced
It increases going across the period as elements gain electrons more easily
It decreases going down a group as the electrons are lost more easily and not gained as easy

15

Core charge(nuclear charge)

The number of positive atoms pulling the valence electrons towards the nucleus. Calculated by atomic number-inner shell electron number

16

Reducing strength

Is how readily an element loses electrons
A reductant causes reduction by losing electrons but is itself oxidised
It decreases across a period as atoms give up their outer shell electrons less readily
It increases down a group as the elements release their electrons more readily

17

Increases across a period

oxidising strength
electronegativity
ionisation energy

18

Decreases going across a period

reducing strength
atomic size
metallic character