(4) Atoms and Isotopes Flashcards
What are the three subatomic particles in a atom?
- proton
- neutron
- electron
Approximately how big is an atom and it’s nucleus?
Atom is 1x10^-10
Nucleus is 1x10^-15
Where are the subatomic particles found in the atom?
The protons and neutrons are in the nucleus giving it a positive charge while the electrons are found in shells/ orbits/ energy levels
What’s the overall charge of an atom?
Atoms are neutral because the positive protons cancel out the negative electrons (same amount)
What is the atomic number?
Number of protons (= to electrons)
What is the mass number?
The number of protons and neutrons added together
What is the isotope of an atom?
Atoms of the same element that have different numbers of neutrons but the same number of protons
Give two ways that an atoms arrangement can be changed:
1) absorbing electromagnetic radiation (electrons move further away from nucleus)
2) emitting electromagnetic radiation (electrons move closer to the nucleus)
How does an atom turn into a positive ion?
Losing 1 or more out electrons
(This means more positive than negative)
What was originally thought about the atom?
A small invisible ball that couldn’t be divided
What did JJ Thomson’s plum pudding model tell us?
That an atom is a ball of positively charged mass, dotted with negatively charge electrons (currents) evenly distributed
Describe the alpha scattering experiment:
Alpha particles were fired at very thin gold foil, most particle went straight through however some were reflected back in different directions (positive alpha repelled by positive nucleus).
Ernest Rutherfords alpha scattering experiment proved what?
- that most of the mass of an atom is concentrated in the centre
- the nucleus is positively charged
- there was a lot of space around the nucleus
What did James Chadwick prove?
The existence of neutrons
