Unit 2 - Atoms and Isotopes Flashcards
In terms of sub atomic particles, What does the mass number of an atom tell us?
The number of protons and neutrons in the centre.
What is an ion?
An atom that has lost or gained electrons.
Why is an atom have no overall charge?
It has an equal number of protons and electrons.
What is an isotope?
An atom of an element with the same number of protons but different number of neutrons. (Isotopes react in the same way but have different masses.)
What is the difference between Carbon-12 and Carbon-14?
Carbon-14 has two more neutrons than carbon-12.
What does the atomic number of an element tell us?
The number of protons it has.
If an element has an atomic number of 9 and a mass number of 19 how many electrons and neutrons does it have?
Electrons = 9 (same number as protons)Neutrons = 10 (19-9)
Give the mass of a proton, neutron and electron.
One, one and zero. All of the mass of an atom is in the middle, the nucleus.
Describe the plum pudding model of the atom.
Positive charge is spread out over the whole atom with electrons dotted around it. The mass is spread out over the whole atom.
Describe the nuclear model of the atom.
A small, positively charged nucleus, where all the mass is concentrated with electrons orbiting in shells around the nucleus. Most of the atom is empty space.
Why did the plum pudding model change into the nuclear model of the atom?
The gold foil experiment provided new evidence that didn’t fit the old model so it had to change to fit with this new evidence.
