1.1 Atomic Structure Flashcards
What is an atom?
The smallest part of an element that can exist on its own
Atoms are the basic building blocks of matter.
State the three subatomic particles.
- Protons
- Neutrons
- Electrons
These particles make up atoms and have different properties.
Who discovered the electron?
Thomson
J.J. Thomson conducted experiments that led to the discovery of the electron.
Describe the ‘plum pudding’ model of the atom.
Negatively charged electrons were embedded in a cloud or sphere of positive charge
This model was proposed by J.J. Thomson.
Who discovered the proton?
Rutherford
Ernest Rutherford’s experiments led to the identification of the proton.
Describe Rutherford’s model of the atom.
Electrons orbited a positively charged nucleus
This model replaced the plum pudding model and introduced the concept of a nucleus.
Who discovered the neutron?
Chadwick
James Chadwick is credited with the discovery of the neutron.
Suggest why the neutron was the last subatomic particle to be discovered.
It is neutral
Neutrons do not carry a charge, making them harder to detect than charged particles.
State the size of a nanometre in metres.
1 x 10^-9 m
A nanometre is one billionth of a metre.
State the size of a picometre in metres.
1 x 10^-12 m
A picometre is one trillionth of a metre.
State the size of a femtometre in metres.
1 x 10^-15 m
A femtometre is one quadrillionth of a metre.
What is the radius of an atom?
0.1 nm / 1 x 10^-10 m
This is a typical size range for atomic radii.
What is the size of the radius of an atom relative to the radius of an atom?
Less than 1/10 000th
This indicates that atomic nuclei are much smaller than the overall size of the atom.
What is the radius of an atom in metres?
1 x 10^-10 m
This is a standard value for atomic radius.
What is the radius of a nucleus of an atom in metres?
1 x 10^-14 m
Nuclei are significantly smaller than the overall atom.
What is meant by the term atomic number?
The number of protons in an atom
The atomic number determines the element’s identity.
What is meant by the term mass number?
The total number of protons and neutrons in an atom
The mass number is used to identify isotopes of an element.
How is the number of neutrons calculated in an atom?
Mass number - atomic number (proton number)
This formula helps to find the number of neutrons.
How is the number of electrons calculated in an atom?
Same as the number of protons
Atoms are neutral, so they have equal numbers of protons and electrons.
Which subatomic particles are in the nucleus of an atom?
- Protons
- Neutrons
Electrons exist in shells surrounding the nucleus.
Which subatomic particle is in the shells of an atom?
Electrons
Electrons occupy energy levels or shells around the nucleus.
What is the relative mass of a proton?
1
Protons have a mass of 1 atomic mass unit (amu).
What is the relative mass of a neutron?
1
Neutrons also have a mass of 1 atomic mass unit (amu).
What is the relative mass of an electron?
1/1840
Electrons are much lighter than protons and neutrons.
