4.2 Isotopes, ions and periodic table

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• Leerjaar 3

Today

- Atoms

- Isotopes

- Ions

- Periodic Table

Symbol	Atomic number	Mass number	#protons	#neutrons	#electrons
Na		23	11		7
Zn	30			36	30
C		15	7		7
Cl	17	36	17

11

12

66

30

7

8

19

17

How many electrons are there in the K-,L- and M-shell of Magnesium?

1. K:2, L:8:M:2
2. K:2, L:4, M:6
3. K:2, L:6, M:4
4. K:2, L:2, M:8

Isotopes

- Different isotopes of a single element occupy the same position on the periodic table. 

- Two types: those found in nature and those found in laboratory

Isotopes

- An isotope is an atom of the same kind with a different atomic mass

- The number of protons is always the same

- The number of neutrons can change

Copper: 2 isotopes in nature

What changes when you deal with isotopes?

1. The atomic mass and the number of elektrons
2. The atomic number and the amount of neutrons
3. The atomic number and the amount of elektrons
4. The atomic mass and the amount of neutrons

Ions

- Special group of atoms where the charge is not 0. 

- Charge=#protons-#elektrons

- Number of electrons can change, not the amount of protons

How many protons and electrons are there in a Ca2+ - ion

1. 20 protons, 20 electrons
2. 20 protons, 18 electrons
3. 18 protons, 20 electrons
4. 18 protons, 18 electrons

Periodic table

- Schematic representation of all the elements we know

- Row: period (7)

- Column: group (18)

- Atomic mass gets bigger from left to right

Important groups:

- Group 1: Alkali metals

- Group 2: Alkaline earth metals

- Group 17: halogens

- Group 18: nobel gasses

All elements want to be a nobel gas, because they are unreactive with perfectly filled shells. Halogens are only one step away from the nobel gasses so they are super reactive. 

Mneumonic	Name	Molecule
Br enda	Bromine	Br 2
O rganises	Oxygen	O 2
N ude	Nitrogen	N 2
F easts	Fluorine	F 2
I n	Iodine	I 2
H er	Hydrogen	H 2
Cl ub	Chlorine	Cl 2

Homework

- Finish questions in 4.1

- Read theory in 4.2

- Exercises of 4.2

https://www.youtube.com/watch?v=m55kgyApYrY