2.1 Periodicity

• Periodicity is a topic that is related to the periodic table, specifically focusing on trends such as the arrangement of elements in the periodic table, the ordering of elements by proton number, and the similar properties of elements in the same group.
• Group one elements have one electron in their outer shell, group two elements have two electrons, and so on.
• The atomic radius increases as you go down a group, facilitating the movement of electrons.
• The melting points of elements increase as you go down a group due to the increased positive charge and delocalized electrons.
• Sulfur has a higher melting point than phosphorus due to its larger molecular size and larger Van der Waals forces.
• Chlorine has a lower melting point than sulfur due to its smaller molecular size and weaker Van der Waals forces.
• Phosphorus has a lower melting point than silicon due to its simple molecular structure and weaker Van der Waals forces.
• Ionization energy is the minimum amount of energy required to remove one mole of electrons from one mole of atoms in the gaseous state.
• Argon, being a monoatomic element, has a lower melting point than chlorine due to its smaller size.
• The toilet radius increases down groups, affecting the movement of electrons.
• Silicon forms a giant covalent structure with many strong covalent bonds, requiring high energy to overcome.
• Elements in the same group have similar properties.
• Elements in the same period have the same number of electron shells.
• Elements in the same period are known as s block elements, P block elements, D block elements, and F block elements.
• Sulfur's outer electron sits in the same 3p orbital as phosphorus, but due to electron repulsion, requires more energy to remove an electron.
• Niels Bohr came up with a shell theory and model which proved accurate but didn't explain data going across a period.
• The modern sub shells orbital and Theory explains the data going across a period.
• Aluminium's outermost electron sits in a higher energy sub shell than magnesium, shielded from the nucleus, requiring less energy for ionization.
• Ionization energy increases as we go across a period due to increased nuclear attraction and the number of protons.
• The highest electron in the highest energy level occupies the S orbital in s block elements, the P orbital in P block elements, the D orbital in D block elements, and the F orbital in F block elements.
• Atomic radius decreases as we go across Period three.
• The decrease in atomic radius is due to an increased nuclear charge as we go across Period three, with more protons in the nucleus pulling in the electrons in the shell but crucially, the shielding effect is similar.
• Ionization energy decreases as we go down a group because it's easier to remove an electron as we go down a group.
• Group 2 is an example of where ionization energy decreases because the atomic radius increases as we go down the group, moving the outer electrons further from the nucleus and weakening the attractive force.
• The more electron shells between the positive nucleus and the outer electron that has been removed, the less energy is required because there is a weak attraction.
• The first ionization of an atom involves removing an electron from an atom, which requires energy.
• Successive ionization involves the removal of more than one electron from the same atom, which is represented by a plus sign (+).
• The atomic size is also important as a bigger atom means a bigger distance between the positive nucleus and the outer electron, making it easier for electrons to be lost.
• The nuclear charge, which is the number of protons in the nucleus, has a bigger impact on ionization as we go down the group.
• Shielding is the protective and the protection of inert electron shells from the nucleus to the outer electron.
• Shielding has a bigger impact on ionization as we go down the group, as more protons are added to the nucleus.
• The second ionization energy is the removal of the second electron, which is represented by a plus sign (+).