Topic 1 - Atomic Structure And The Periodic Table Flashcards
What does an atom contain?
Protons, neutrons and electrons
How big is the radius of an atom?
About 0.1 nanometers
What are features of the nucleus of an atom?
Its in the middle of the atom. Contains protons and neutrons. Radius of about 1 x 10^-14 Positively charges Where most of the mass of an atom is concentrated.
What are the features of an electron?
Moves around the nucleus in electron shells.
Negatively charged
Volume of their orbit determines the size of the atom.
Have virtually no mass.
Whats the difference between an ion and an atom?
An ion has more/less electrons than protons which then gives itself a charge.
An atom is neutral since the amount of protons and electrons cancel each other out.
Which number on the periodic table is the mass number and atomic number?
Mass number is the bigger number (top)
What does the atomic number tell you?
Amount of protons
What does the mass number tell you?
Total number of protons and neutrons
What is an element?
A substance that only contains atoms with the same atomic number
What is an isotope?
They are different forms of the same element with same number of protons but different number of neutrons. So same atomic number but different mass numbers.
How do you find relative atomic mass? (Ar)
Ar = sum of (isotope abundance x isotope mass number) / sum of all abundances
What is a compound?
Substances formed from 2 or more elements. The atoms of each are in fixed proportions and are held together by chemical bonds.
What are the features of a compound formed from a metal and non metal?
Consists of ions.
Metal loses electrons to form positive ions and non metal gains electrons to form negative ions.
Opposite charges of ions means they strongly attract to each other.
What are the features of a compound formed from 2 non metals?
Consists of molecules.
The atoms share electrons which other atoms (covalent bonding).
Fill in the blanks. Just as elements are represented with _____ , compounds are represented with _____.
1) Symbols
2) Formulas
What is a mixture?
2 or more elements mixed together but the atoms are not chemically bonded.
Eg air is a mixture of gases like oxygen, nitrogen, carbon dioxide and argon.
How can you use filtration to separate a mixture?
Can be used to separate insoluble solids from a liquid.
Can also be used for purification
How can you use evaporation to separate a mixture?
Separate soluble solid from a liquid
1) Pour solution into evaporating dish.
2) Slowly heat the solution. The solvent will evaporate and solution will get more concentrated. Eventually, crystals will start to form.
3) Keep heating evaporating dish until all you have left are dry crystals
How can you use crystallisation to separate a mixture?
Separate soluble solid from liquid if the salt decomposes when heated.
1) Pour solution into evaporating dish and gently heat the solution.
2) Once some solvent has evaporated, or when you see crystals start to form, remove dish from heat and leave solution to cool.
3) The salt should start to form crystals it becomes insoluble in the cold, highly concentrated solution.
4) Filter crystals out of solution and dry them
How can you separate rock salt? (Sand and salt mixed)
1) Grind mixture to make sure the salt crystals are small.
2) Put mixture in water and stir. The salt will dissolve but sand won’t.
3) Filter mixture. The sand wont fit through but the salt water will.
4) Evaporate the water from the salt
At the start of the 19th century who described atoms as solid spheres?
John Dalton
Who, in 1897 concluded that atoms had electrons and what theory was this?
J J Thomson.
The theory was called ‘The plum pudding model’.
The plum pudding model showed an atom as a ball of positive charge with electrons stuck on it.
Who in 1909 conducted the alpha particle scattering experiments and what did he conclude from this?
Rutherford.
He shot positively charged alpha particles and a thin sheet on gold expecting particles to pass straight through or be slightly deflected at most.
Most did go through but more than expected were deflected which led to the discovery if the nucleus which deflected alpha particles
Who discovered that electrons orbit the nucleus in fixed shells?
Bohr
