Chemistry - C1.1 and 2.1 test revision Flashcards
All substances are made from what?
tiny partcles called atoms
What are elements
a substance made up of only one type of atom
WHat are compounds
subtstances made up of different types of atoms bonded together
What do chemical bonds do?
they hold the atoms tightly together in compounds
what are all atoms made up of?
a tiny central nucleus with electrons orbiting around it
What do most compounds consist of?
more than two different types of atom.
WHat did mendeleev do for elements that had not yet been discovered?
He left gaps
What order did mendeleev place place the elements in?
in the order of atomic weights
Whhat did mendeleev predict with the gaps in his periodic table?
the properties of the undiscovered elements
what was john newlands periodic table called?
his ‘law of octaves’, as every eighth elements’ properties seemed similar
What did john newlands do with his table that was wrong?
he assumed that all the elements had been found
HOw was mendeleevs table arranged?
it was arranged so you could see elements with similar properties in the same group
What was the problem with mendeleevs table?
with new elements, Mendeleev simply changed the order where necessary to keep the elements with similar properties in a group
