Physics Flashcards
Most of the mass of an atom is contained within a small dense ____. The nucleus is made of _____ and _____
nucleus
protons
neutrons
Protons have a _____ charge and _____ have zero charge. Electrons ____ around the nucleus.
positive
neutrons
orbit
Electrons have a negative charge and a small ____
mass
The atomic number of an element tells us how many _____ are in the nucleus. The element will also have the same number of ______
protons
electrons
The atomic mass of the electrons tells us how many protons and _____ there are in the ______
neutrons
nucleus
To calculate the number of neutrons, we subtract the atomic ______ from the atomic _____
number
mass
What makes hydrogen unique when compared to other elements?
No neutrons
Isotope
Has the same number of protons and electrons but a different number of neutrons
What is the atomic structure of a ‘normal’ hydrogen
One proton in nucleus and one electrons orbiting the nucleus
What is the difference between an ion and an atom
An ion is a charged atom
If an atom gains one electron, what would it’s overall charge be?
-1
If an atoms loses one electron, what would it’s overall charge be?
+1
Alpha radiation; 1) description 2) electric charge 3 )relative atomic mass 4) penetrating power 5) ionizing effect 6) effect of magnetic/electric field
1) 2 neutrons, 2 protons. An alpha particle is the same s a helium nucleus
2) +2
3) 4
4) stopped by paper or a few cm of air
5) strongly ionizing
6) weakly deflected
Beta radiation;
1) description
2) electric charge
3) relative atomic mass
4) penetrating power
5) ionizing effect
6) effect of magnetic/electric field
1) high energy electron
2) -1
3) 1/2000
4) stopped by a few mm of aluminium
5) weakly ionizing
6) strongly deflected
Positron (beta plus) radiation;
1) description
2) electric charge
3) relative atomic mass
4) penetrating power
1) high energy and high speed particle/ positive electron/ antimatter
2) +1
3) 1/2000
4) annihilates immediately
Gamma radiation;
1) description
2) electric charge
3) relative atomic mass
4) penetrating power
5) ionizing effect
6) effect of magnetic/electric field
1) high energy electromagnetic radiation
2) 0
3) 0
4) stopped by several cm of lead or several m of concrete
5) very weakly ionizing
6) not deflected
What happens to cause an atom to emit energy?
an electron moves to a higher orbit (energy level)
What happens when an atoms absorbs energy?
An electron moves to a lower orbit
What happens when an atom becomes an ion?
The electron completely leaves the orbits
The first person to suggest the idea of atoms was the Greek philosopher _______. This idea is a substance is called an element.
Democritus 4500BC
The idea that the atomic structure have changed over time. _____ reintroduced the idea that everything is made of atoms. He said atoms were solid of spheres of matter that could not be split.
John Dalton, 1803
The discovery of radioactivity. In a radioactive atom, the nucleus is unstable and so it emits particles or waves of radiation to form a more stable atom.
Henri Becquerel, 1896
The discovery of tiny particles with a negative charge. Also discovered the existence of electrons. It didn’t fit with Dalton’s model so created a new one. - PLUM PUDDING MODEL
J.J Thomson, 1897
Came up with his ‘nuclear’ model of the atom. He made many important discoveries about radioactivity and atomic structure.
Ernest Rutherford, 1911
