Atomic structure Flashcards
Which atomic model does this show?
Plum pudding model
Who developed the plum pudding model?
JJ Thompson
Describe John Dalton’s model of the atom.
Atoms are tiny spheres that cannot be divided.
Describe the plum pudding model of the atom.
The atom is a ball of positive charge with negative electrons embedded in it.
Who carried out the alpha particle scattering experiment?
Ernest Rutherford
Describe the alpha particle scattering experiment.
- Positively charged alpha particles were fired at thin gold foil
- Most alpha particles went straight through the foil
- A few alpha particles were scattered in different directions
Who developed the nuclear model?
Rutherford
Describe the nuclear model.
- The mass of an atom is concentrated in the centre, the nucleus
- The nucleus is positively charged
Who developed the theory that electrons orbit the nucleus in shells?
Niels Bohr
What is the charge on a proton?
+1 (positive)
What is the charge on an electron?
-1 (negative)
What is the charge on a neutron?
0 (neutral)
Which two subatomic particles are found in the nucleus?
- Protons
- Neutrons
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
What is the relative mass of an electron?
Almost 0 (negligible)
What is the atomic number?
The number of protons in an atom
Why does an atom have no overall charge?
An atom has equal numbers of protons (positive) and electrons (negative)
What is the atomic number of sodium?
11
How many protons are in an atom of oxygen?
8
What does the mass number represent?
The total number of protons and neutrons in an atom
How many neutrons does this sodium atom have?
12 neutrons
How can you calculate the number of neutrons an atom has?
Mass number - atomic number
What is an isotope?
Atoms of the same element with different numbers of neutrons
Why do all isotopes of the same element have the same properties?
Because they have the same number of electrons
What is the relative atomic mass?
The mean relative mass of the atoms of the different isotopes of an element
75% of chlorine atoms have a mass number of 35.
25% of chlorine atoms have a mass number of 37.
What is the relative atomic mass of chlorine?
35.5
