3.1. The atomic model lesson 2

• Scheikunde
• Middelbare school
• havo, vwo
• Leerjaar 3

 3.1. The atomic model - isotopes

3. The structure of substances

Atomic model

An atom is composed of protons, neutrons and electrons.
The 1+ charged protons (p) and the neutral neutrons (n) are in the atomic nucleus
The 1− charged electrons (e^-) are in a cloud around the atomic nucleus.

Number of particles

• atomic number = number of protons
  (determines type of atom)

• number of electrons = number of protons (no charge)
  

• mass number = number of protons + number of neutrons

Isotopes

The same element - different mass

Same number of protons; different number of neutrons

Other notation: P-31 

Notation of isotopes

Isotopes

Types of substances

Type	Consist of
Metal	metal-atoms
Molecular substance	non-metal atoms
Salt	metal- and non-metal atoms

Types of substances

Type	Solid	Liquid	Dissolved in water
Metal	yes	yes	-
Molecular substance	no	no	no
Salt	no	yes	yes

What type of substance conducts electricity at the solid phase?

1. Metals
2. Salts
3. Molecular substances

What type of substance consists of a metal and a non-metal

1. Molecular substances
2. Metals
3. Salts

Sodium has atomic number 11 and mass number 24. How many protons does sodium have?

1. 11
2. 12
3. 23
4. 34

Sodium has atomic number 11 and mass number 24. How many electrons does sodium have?

1. 11
2. 12
3. 13
4. 34

Sodium has atomic number 11 and mass number 24. How many neutrons does sodium have?

1. 11
2. 12
3. 13
4. 24

When a neutron joins the nucleus then ...

1. the atom number becomes higher
2. the atom number becomes lower
3. the mass number becomes higher
4. the mass number becomes lower

N-14 has 7 protons and 7 neutrons.
C-14 has 6 protons and 8 neutrons.
N-14 and C-14 are isotopes

1. true
2. false