Materials Flashcards
What did Thomson do?
Develop the plum pudding model-positively charged atoms with electrons embedded in them. 1903
What did Bohr do?
Create the shell model-atoms consisting of a positive nucleus with electrons in certain orbits or fixed energy called shells. 1913
What did Rutherford do?
Create the solar system model-the atom was a mostly empty space with a positively charged nucleus and electrons orbiting the nucleus. 1911
What did Chadwick do?
He added neutrons to the shell model, this is the model we use. 1932
How many electrons fit in the first three shells of an atom?
2,8,8
What is an electron?
A negative subatomic particle that orbits the nucleus in fixed shells of energy
What is the nucleus of an atom made up of?
Neutrons(neutral) and protons(positive)
What is the mass of a proton/neutron?
1
What is the mass of an electron?
0
What is the top number on an atom on a periodic table?(atomic number)
The amount of protons and neutrons
How do you find the amount of neutrons?
Atomic mass minus atomic number
What are electrons in the outmost shell called?
Valence electrons
What are 4 properties of metals?
Good conductors of electricity, good conductors of heat, malleable and ductile
What are pure metals?
Metals found as jut itself in nature-not in an alloy or ore
What are alloys?
Two metals mixed together
What is a base metal?
A metal that goes into an alloy
Two examples of alloys
Brass and bronze
What is the advantage of an alloy over it’s base metal?
It has the properties of both metals
What are uses and properties of brass?
Uses-it can be used for decoration, plumbing and electrical, things requiring low friction like doorknobs, locks, and musical instruments.
Properties- low friction, highly workable and durable
What are the properties and uses of bronze?
Uses- coins, springs, turbines and blades
Properties- good conductors and low friction
What does an acid give off when put in water?
An H+ ion
What does an alkali/base give off in water?
An (OH)- ion
What is an ion?
A charged atom
What are the properties of acids?
Can be corrosive, sour to taste, found in sour foods, eg. Vinegar and less than 7 on the pH scale
What are the properties of alkalis/bases
Can be caustic, bitter to taste, used in cleaning products and have a pH more than 7
What is pH?
A measure of acidity and alkalinity where each number is ten times bigger than the last
What is the neutralisation reaction?
Acid+base—–>salt+water
Eg. HCl+NaOH—–>NaCl+H2O
Why do we need to develop new materials?
Most plastics are made from oil, a finite source
How have plastics improved?
Rather than thermo setting plastic which can’t melt once its set, we have thermal plastics with can be melted and therefore recycled etc. they are also cheaper
What did Democritus do?
He made the indivisible particle model. 350BC
Element
Pure substance made up of one type of atom
Compound
Pure substance made up of two or more atoms chemically combined in fixed ratios
