Atomic structure and the periodic table Flashcards
What is in a nucleus
- Neutrons
- Protons
What is the radius of a atom
0.1 nm
Radius of a nucleus
1 x 10*-14 m
What is the relative mass of protons, neutrons and electrons
proton - 1
neutron - 1
electron - very small
What is the relative charge of the neutron, electron and proton
Proton = +1 neutron = 0 electron = -1
What is the mass number on an atom in the periodic table
The top number
= total number of protons and neutrons in an atom
What is the atomic number
the bottom number and is the number of protons
elements
substances made up of atoms with the same atomic number
isotopes
atoms with the same number of protons but different number of neutrons
relative atomic mass
the average mass number of an element
Compounds
substances formed from two or more elements chemically bonded together in fixed proportions
Molecule
Particles containing two or more non-metal atoms bonded covalently
Mixtures
Substances are made up of different elements or compounds that aren’t chemically bonded to each other
example - air is a mixture (oxygen, carbon dioxide)
How can mixtures be separated
By physical methods like filtration
What is filtration
separates insoluble solids from liquids and solutions, it can be used to purify a liquid
Evaporation
Separates soluble salts from a solution
Crystallisation
Separates soluble salts from a solution
Simple distillation
separates solutions by heating up the solution and the liquid with the lower boiling point evaporates
Then cools and condenses and pours into a separate flask
As a result, two separated liquids
What is a disadvantage of simple distillation
Cannot separate liquids with similar boiling points
Fractional distillation
Watch video or look at book
History of the atom
. Plum pudding model (ball of positive with negative floating around)
- J J Thomspon
.Nuclear model - positive nucleus and a ball of electrons around, mostly empty space
- Ernest Rutherford
. Bohr model - electrons orbit nucleus in fixed shells
- Neils Bohr
.James Chadwick proved neutrons were neutral in the nucleus
Electronic structure
Electrons orbit around the nucleus in energy levels
The periodic table history
Before atomic structure was discovered, atomic weight was used to order elements
Mendeleev’s table
The elements were grouped by properties instead of strictly following atomic weight
swapped elements around in places where ordering didn’t fit the parrern
The modern periodic table
ordered by increasing atomic number
Group Number = The number of electrons in the outer shell
Period Number = The number of energy levels with electrons in
Metals
Elements that can form positive ions when they react
lose electrons