Elements, atomic structure, compounds and mixtures

Question 1

element defintion

Answer 1

substances that cannot be broken down into anything simpler : made up of one type of atom

Question 2

compound defintion

Answer 2

substances that contain two or more chemically combined elements.
in a fixed ratio

Question 3

mixture defintion

Answer 3

substances that contain two or more elements or compounds in a variable ratio that are not chemically bonded, can be separated with ease

Question 4

molecule defintion

Answer 4

two or more atoms or compounds joined by a covalent bond

Question 5

what did dalton state about the atom

Answer 5

tiny solid balls - like billiard balls
are tiny invisible particles
atoms of one element are the same
atoms of different elements are different
compounds are formed by combining atoms

Question 6

what did jj Thomson discover

Answer 6

electrons using cathode rays
first scientist to show that atoms are made up of smaller things
plum pudding model - electrons are like raisins inside a positively charged pudding

Question 7

what did Ernest rutherford discover about atoms

Answer 7

published results of his gold foil experiment, where he sent a beam of alpha particles at a thin piece of gold. based on ppm, they should’ve gone straight through the foil, but they were scattered at multiple different degrees. he concluded :
atoms are 99% atom space
must be a dense positive centre, called th nucleus, made up of protons
alpha and centre must be the same charge - positive

Question 8

what did Niels Bohr propose about the atom

Answer 8

electrons move around in specific shells
every atom has a specific number of electron shells

Question 9

what did James Chadwick discover about the atom

Answer 9

neutron - found in the nucleus with the proton