Topic 1 Flashcards
What are the three sub-atomic particles?
- Proton
- Neutron
- Electron
Protons and neutrons are found in the nucleus, while electrons occupy orbitals.
What is the position and charge of a proton?
Position: Nucleus
Charge: +1
Protons have a relative mass of 1.
What is the position and charge of a neutron?
Position: Nucleus
Charge: 0
Neutrons have a relative mass of 1.
What is the position and charge of an electron?
Position: Orbitals
Charge: -1
Electrons have a relative mass of 1/1840.
What is the atomic number (Z)?
Number of protons in the nucleus
It defines the identity of an element.
What is the mass number (A)?
Total number of protons and neutrons in the atom
It can be calculated using the formula: A = Z + Number of Neutrons.
Define isotopes.
Atoms with the same number of protons but different numbers of neutrons
Isotopes have similar chemical properties but may have different physical properties.
What is relative isotopic mass?
Mass of one atom of an isotope compared to one twelfth of the mass of one atom of carbon-12
It helps in determining the masses of isotopes.
Define relative atomic mass.
Average mass of one atom compared to one twelfth of the mass of one atom of carbon-12
It is a weighted average of all isotopes.
Define relative molecular mass.
Average mass of a molecule compared to one twelfth of the mass of one atom of carbon-12
It is calculated similarly to relative atomic mass.
What is the function of a mass spectrometer?
Determines all isotopes present in a sample and identifies elements
It measures m/z (mass/charge ratio) and abundance.
How is relative atomic mass calculated?
R.A.M = Σ (isotopic mass x % abundance) / 100
This formula provides the weighted average of isotopes.
What happens when two electrons are removed from a particle?
Forms a 2+ ion
Example: 24Mg2+ has a m/z of 12.
What is the first ionisation energy?
Energy required when one mole of gaseous atoms forms one mole of gaseous ions with a single positive charge
Represented by the equation: H(g) → H+(g) + e-.
What is the second ionisation energy?
Energy required when one mole of gaseous ions with a single positive charge forms one mole of gaseous ions with a double positive charge
Represented by the equation: Ti+(g) → Ti2+(g) + e-.
What are the three main factors affecting ionisation energy?
- Attraction of the nucleus
- Distance of electrons from the nucleus
- Shielding effect
These factors influence the energy required to remove electrons.
Why are successive ionisation energies always larger?
The first electron removal creates a positive ion, increasing the attraction on remaining electrons
This means more energy is required to remove subsequent electrons.
What is periodicity?
Repeating pattern across a period in the periodic table
It can be observed in first ionisation energies and atomic radii.
Why does helium have the largest first ionisation energy?
Its first electron is closest to the nucleus with no shielding effects from inner shells
Helium has more protons than hydrogen, increasing attraction.
Why do first ionisation energies decrease down a group?
Outer electrons are further from the nucleus and more shielded, reducing nuclear attraction
This makes it easier to remove outer electrons.
Why is there a general increase in first ionisation energy across a period?
Increasing number of protons increases effective nuclear attraction on electrons in the same shell
Electrons are pulled closer to the nucleus.
What is the shape of the graph for first ionisation energy across periods two and three?
Similar shape showing a repeating pattern
Peaks and drops occur due to electronic structure changes.
What happens to the melting and boiling points of elements across a period?
They vary due to differences in bonding types
Metallic bonds are stronger with more electrons, while simple molecular compounds have weaker London forces.
What is the electronic structure of Mg and Mg2+?
Mg: 1s2 2s2 2p6 3s2, Mg2+: 1s2 2s2 2p6
The positive ion loses two electrons.
