Elements, Compounds And Mixtures Flashcards
What is an element?
Substance that can’t be broken down into other substances. It is a pure substance only made up of one atom.
What is the atomic number?
The number of protons in the nuclei of its atoms.
Which types of substances did blacksmiths try and help us to understand?
They helped us to understand many substances we use in everyday life.
What is an atom?
Atoms are made up of 3 sub atomic particles; protons, neutrons and electrons. Electrons orbit the nucleus which is located at the centre of the atom and houses the protons and neutrons.
Are protons negatively charged?
No
Are electrons negatively charged?
Yes
What problems were the alchemists of medieval times trying to solve?
They tried to change metal into gold and also tried to find a potion that would make humans live forever.
What are the eight metalloids?
Boron, silicon, arsenic, germanium, antimony, polonium, astatine, tellurium.
Features of metal
Solid at room temp, except Mercury (liquid)
Polished to produce a high shine or lustre
Good conductors of heat
Beaten or bent into a variety of shapes (malleable)
Made into wire (ductile)
Melt at high temps (apart from Mercury which is at -40 degrees Celsius)
Features of solid non metals
Can't be polished (dull/glassy) Brittle (shatter when they are hit) Can't be bent Usually poor conductors of electricity and heat Usually melt at low temps
How many elements are non metals?
22
11 are gases, ten are solid and 1 is a liquid
What are metalloids?
Elements that have features of both metals and non metals
How many elements were discovered between 1557 and 1925?
76
What was the name of the job to study atoms?
Scientist
Do neutrons have a charge?
No
Is a nucleus positive or negative?
Positive
When did sir Ernest Rutherford use some of the new discoveries and inventions to prove that atoms were not solid particles?
1911
Who proved the second model of the atom and what was different?
Niels Bohr. He suggested that the electrons changed their orbit around the positively charged nucleus and formed electron clouds.
In 1932 who found the neutron?
James Chadwick found another type of particle in the nucleus of the atom - the neutron.
Atoms are made up of:
Small particles
