atomic structure and the periodic table Flashcards
(16 cards)
What is an isotope?
An element with the same number of protons but a different number of neutrons
What is a compound?
Two or more elements that are chemically bonded
What is a mixture?
Multiple elements and/or compounds that are not chemically bonded
How was an atom believed to be formed before the 1800s?
Indivisible tiny spheres
What did JJ Thompson think about the atom in 1897?
He discovered electrons which led to the plum pudding model; a ball of positive charge with electrons embedded in it.
What did Ernest Rutherford think about the atom in 1909?
He carried out the alpha particle scattering experiment which led to the conclusion that the mass was concentrated in the centre and that the nucleus was charged.
What did Ernest Rutherford think about the atom in 1920?
Positive charge can be divided into smaller particles (protons)
What did Niels Bohr think about the atom in 1911?
Electrons orbit the nucleus at specific distances
What did James Chadwick think about the atom in 1940?
Provided evidence on the existence of neutrons in the nucleus 20 years after the scientific acceptance of atoms
What is the mass and charge of a proton?
1, +1
What is the mass and charge of a neutron?
1, 0
What is the mass and charge of an electron?
negligible, -1
How is the Relative Formula Mass (Mr) calculated?
What is group 7?
The Halogens: They are very reactive non-metals with 7 electrons on the outer shell. They are diatomic and reactivity decreases and melting + boiling points increase asn you go down the table. They react strongly with group 1.
What is group 0?
The Noble Gases: They are unreactive non-metals with 8 electrons on the outer shell. Boiling points increase as you go down the table.
What is group 1?
The Alkali Metals: They have 1 electron on the outer shell. Reactivity increases and boiling points decrease as you go down the table. They react strongly with group 7, water, and oxygen.
