Atomic Physics
ATOMIC PHYSICS
The nuclear atom
All matter is made up of atoms which consist of a central nucleus, surrounded by electrons. Inside the nucleus are protons and neutrons.
Particle Relative mass Charge Location
Proton 1840 + Nucleus
Neutron 1840 0 Nucleus
Electron 1 - Outside nucleus
Proton or atomic number (Z)
This is the total number of protons in the nucleus of an atom.
Nucleon or mass number (A)
This is the total number of protons and neutrons in the nucleus of an atom.
Note: a nucleon is a particle found in the nucleus i.e. a proton or a neutron.
In general, if N is the neutron number of an element, then
A=Z+N
In an atom the number of protons is equal to the number of electrons.
Nuclide notation
A nuclide is a form of an element.
If X is a given nuclide with proton number Z and nucleon number A, then its nuclide notation will be:
(_Z^A)X
Examples The nuclide notation for some atoms is as indicated below: Hydrogen:(_1^1)H carbon: (_6^12)C sodium: (_11^23)Na Uranium: (_92^238)U
Write down the number of protons, electrons and neutrons in each of the atoms in example1 above: Hydrogen:(_1^1)H
Protons = 1, electrons = 1, neutrons = 1 – 1= 0 carbon: (_6^12)C
Protons = 6, electrons = 6, neutrons = 12 – 6= 6
sodium: (_11^23)Na
Protons = 11, electrons = 11, neutrons = 23 – 11= 12
Uranium: (_92^238)U
Protons = 92, electrons = 92, neutrons = 238 – 92= 146
Isotopes
Isotopes are atoms of the same element which have the same number of protons but different numbers of neutrons. That is, their proton numbers are the same but their nucleon numbers are different.
Examples
Hydrogen: (_1^1)H: (_1^2)H: (_1^3)H Carbon: (_6^12)C: (_6^14)C Chlorine: (_17^35)Cl: (_17^37)Cl Uranium : (_92^235)U: (_92^238)U Isotopes have the same chemical properties because they have same number of protons (or electrons). They have different physical properties since they have different mass numbers.
Radioactivity
Radioactivity is the
The nuclear atom
All matter is made up of atoms which consist of a central nucleus, surrounded by electrons. Inside the nucleus are protons and neutrons.
Particle Relative mass Charge Location
Proton 1840 + Nucleus
Neutron 1840 0 Nucleus
Electron 1 - Outside nucleus
Proton or atomic number (Z)
This is the total number of protons in the nucleus of an atom.
Nucleon or mass number (A)
This is the total number of protons and neutrons in the nucleus of an atom.
Note: a nucleon is a particle found in the nucleus i.e. a proton or a neutron.
In general, if N is the neutron number of an element, then
A=Z+N
In an atom the number of protons is equal to the number of electrons.
Nuclide notation
A nuclide is a form of an element.
If X is a given nuclide with proton number Z and nucleon number A, then its nuclide notation will be:
(_Z^A)X
Examples The nuclide notation for some atoms is as indicated below: Hydrogen:(_1^1)H carbon: (_6^12)C sodium: (_11^23)Na Uranium: (_92^238)U
Write down the number of protons, electrons and neutrons in each of the atoms in example1 above: Hydrogen:(_1^1)H
Protons = 1, electrons = 1, neutrons = 1 – 1= 0 carbon: (_6^12)C
Protons = 6, electrons = 6, neutrons = 12 – 6= 6
sodium: (_11^23)Na
Protons = 11, electrons = 11, neutrons = 23 – 11= 12
Uranium: (_92^238)U
Protons = 92, electrons = 92, neutrons = 238 – 92= 146
Isotopes
Isotopes are atoms of the same element which have the same number of protons but different numbers of neutrons. That is, their proton numbers are the same but their nucleon numbers are different.
Examples
Hydrogen: (_1^1)H: (_1^2)H: (_1^3)H Carbon: (_6^12)C: (_6^14)C Chlorine: (_17^35)Cl: (_17^37)Cl Uranium : (_92^235)U: (_92^238)U Isotopes have the same chemical properties because they have same number of protons (or electrons). They have different physical properties since they have different mass numbers.
Radioactivity
Radioactivity is the