Chemistry Atomic structure, Covalent bonding and Metallic bonding half term test Flashcards
What’s the order of the development of the atomic models?
- Greeks said that atoms are tiny spheres that cannot be divided
- Plum pudding model, a ball of positive charge with electrons embedded in it
- Alpha particle scattering experiment, showed that the mass of an atom is concentrated at the centre and the nucleus is charged
- Positively charged nucleus orbited by electrons like planets around the sun
- Niels Bohr adopted the nuclear model by suggesting that the electrons orbit at specific distances
Definition of atom
Smallest part of an element that can exist
Definition of element
Contains only one type of atom
Definition of compound
consists of two or more elements or compounds that are chemically combined
How to calculate relative atomic mass
Total mass of atoms/ total number of atoms
What are isotopes?
atoms of the same element but with different numbers of neutrons therefore different masses.
Who discovered the neutron?
James Chadwick
What is covalent bonding?
When atoms share pairs of electrons. (strong bond)
Advantages of displayed formula
- quick and easy to draw and identify
- shows how they are bonded to each other
Advantages of ball and stick models
- shows the shape of the molecule
- 3D
- shows which atoms are bonded to which
Advantages of dot and cross diagrams
- shows which atoms are bonded to each other
- shows electrons
Disadvantages of displayed formula
- 2D
- cannot see electrons
Disadvantages of ball and stick models
- does not show electrons
- hard to draw when there are many atoms
Disadvantages of dot and cross diagrams
- does not show electrons orbiting
- hard to draw if there are many atoms
- 2D
Size of atom
1 nanometer (1x10^-10m)
Size of nucleus
About 1x10^-14m