AS-Level Chemistry :Paper 1 2024 latest update graded a+

AS-Level Chemistry :Paper 1 2024 latest update graded a+ Arranged in periods (rows) and groups (columns) by atomic (proton) number - CORRECT ANSWER-How is the periodic table arranged Have the same number of electrons shells, even if they are not all parts of the s or p sub-shells - CORRECT ANSWER-All elements within a period ... Have the same number of electrons in their outer shell, meaning that they all have similar properties - CORRECT ANSWER-All elements within a group ... Periodicity - CORRECT ANSWER-The trends in the physical and chemical properties of elements as you go across the periodic table. Atomic radius across period 3 - CORRECT ANSWER-Atomic radius across period 3 goes as follows: 1) As the number of protons increases the further down a period you go, the positive charge of the nucleus increases 2) And though the amount of electrons increases across a period, they are added to the outer energy level - So their isn't any extra shielding 3) This means that the electrons are pulled closer to the nucleus, causing the atomic radius to decrease 4) Therefore, that overall the atomic radius of an atom decreases across period 3 with the largest radius being the first element, Na, and the smallest being the last element, Ar Melting points across a period 3 - CORRECT ANSWER-The melting point across period 3 goes as follows: 1) At the start with sodium, magnesium and aluminium their melting points increase. This is because they are metals and have strong electrostatic forces to overcome - The bonds get stronger by the time you reach Al due to having and more positively charged nucleus, increased number of delocalised electrons and a decreasing radius 2) From Al to Silicon, the melting point increases further as Si is a macromolecular substance which has very strong covalent bonds that take a lot of energy to break 3) However, the melting point then drops due to phosphorus, sulfur, chlorine and argon all being molecular substances. The issue with being that kind of substance is that to break the bonds apart all you need to do is to overcome the weak Van der Waals forces - A very easy task 4) The difference in melting points between P, S, Cl and Ar is that some molecules are bigger than others which leads to slightly greater Van der Waals forces First ionisation energy across period 3 - CORRECT ANSWER-First ionisation energy across period 3 goes as follows: