Atomic Structure And The Periodic Table Flashcards
What are atoms
The smallest pieces of an element that can exist
They have a radius of 1 x 10^-10 m
Radius of nucleus is 1 x 10^-14
What are compounds
Contains at least 2 different elements
Atoms of different elements combine to form compounds
What are elements
Substance of one type of atom
What are mixtures
Made up of 2 or more substances that haven’t been chemically bonded togerher
What are examples of separation techniques
Crystallisation
Chromatography
Filtration
Simple distillation
Fractional distillation
A what is crystallisation
Separates solutions into their constituent parts-dissolved solids and liquids
Heat the mixture so the solvent evaporates
Cool the solution and the solid starts to crystallise as it becomes less soluble at lower temps
What’s chromatography
Separates solutions with a number of diff solutes in the solvent
Place a piece of paper with a spot containing a mixture in beaker with solvent
Solvent level slowly rises separating the mixture into components
What’s filtration
Separated mixtures of insoluble solids and liquids. Done by pouring the mixture through filter paper because the particles are too big to fit through the paper
Filtrate is substance that comes through
What is distillation
Special technique used to separate mixtures of liquids. It used the different boiling points of liquids to separate them
What did JJ Thompson discover in 1897
Electrons
How did Jj Thompson discover electrons
He modelled it as a “plum pudding” a ball of positive charge with negatively charged electrons mixed in with the dough
What did Ernest Rutherford calculate in 1909
Discovered that alpha particles could bounce off of atoms
Concluded that an atoms mass is concentrated in its centre. Called the nucleus and contained positively charged protons
How did Ernest Rutherford discover the nucleas in 1909
A beam of alpha particles was aimed at very thin gold foil and their passage through was detected
Some of the alpha particles emerged from the fo I’ll at different angles and some came straight back
Most particles went through showing it was mostly empty space
What did Niels Bohr conclude
That electrons orbited the atom at fixed distances
Later showed positive charge of any Nucleas could be subdivided into a while number of smaller particles each having the same amount of positive charge
What did James Chadwick discover in 1932
That some particles in the nucleus had no charge at all. He called them neutrons
What are the three different subatomic particles
Protons
Neutrons
Electrons
What is the info about protons
Relative charge of +1
Found in the nucleus
Relative mass of 1
What is the information about neutrons
Neutrons have no charge
Found in the nucleus
Relative mass of 1
What is the information on electrons
Relative charge of -1
Found in fixed orbits around the nucleus
Very small mass
How do you find the number of protons and electrons in an atom
By identifying the atomic number which is the bottom number
How do you find the number of neutrons in an atom
By subtracting the mass number (top number) from the atomic number (bottom number)