Chemistry Paper 1 (Atomic Structure & The Periodic Table; Bonding, Structure & The Properties of Matter; Quantitative Chemistry, Chemical Changes; and Energy Changes): Exam Questions with Complete Solutions 2024/2025

1. How long is Paper 1, and what does it assess? - Ans .Paper 1 of the AQA GCSE Higher Chemistry (Single Science) course lasts for 1 hour and 45 minutes, and assesses content from Atomic Structure & The Periodic Table; Bonding, Structure & The Properties of Matter; Quantitative Chemistry, Chemical Changes; and Energy Changes. 2. What is the radius of an atom? - Ans .The radius of an atom is 0.1 nanometers (1x10^-10m). 3. What are the masses and charges of the three subatomic particles that make up an atom, and where are they located? - Ans .Protons have a mass of 1 and a charge of +1 (positive). They are located in the nucleus. Neutrons have a mass of 1 and a charge of 0 (neutral). They are located in the nucleus. Electrons have a mass of 0 (0.005 / negligible) and a charge of -1 (negative). They are located in varying energy levels around the nucleus, or 'shells'. 4. What is the radius of the nucleus of an atom? - Ans .The radius of the nucleus of an atom is 1x10^-14 m. 5. What is the relationship between the number of protons and the number of electrons in an atom? - Ans .number of protons = number of electrons 6. How is the mass of an atom (not element) calculated? - Ans .mass of atom = number of protons + number of neutrons 7. What are charged atoms called? - Ans .Charged atoms are called ions. It is important to note that atoms have no charge - 'charged atoms' do not exist, only ions, which are formed when an atom gains a charge. 8. What is an element? - Ans .An element is a substance made up of atoms that all have the same number of protons in their nucleus. 9. What is a chemical symbol? - Ans .A chemical symbol uses one or two letters to refer to elements. According to the IUPAC (International Union for Pure & Applied Chemistry), chemical symbols must be derived from the element's name in English, Latin, or Greek. 10. What are isotopes? - Ans .Isotopes are atoms of the same element (the same number of protons) with different numbers of neutrons. 11. What is the formula for relative atomic mass? - Ans .Relative atomic mass (Ar) = (Σ (isotope abundance x isotope mass number))/Σ isotope abundance 12. What are compounds? - Ans .Compounds are substances formed from two or more elements. The atoms of each element are in fixed proportions throughout the compound and they are held together by chemical bonds. 13. State are the formulas for the following compounds: carbon dioxide, ammonia, water, sodium chloride, carbon monoxide, hydrochloric acid, calcium chloride, sodium carbonate and sulfuric acid. - Ans .Carbon dioxide = CO2, Ammonia = NH3, Water = H2O, Sodium chloride = NaCl, Carbon monoxide = CO, Hydrochloric acid = HCl, Calcium chloride = CaCl2, Sodium carbonate = Na2CO3, Sulfuric acid = H2SO4 14. Where are the reactants and products located in a chemical equation? - Ans .In a chemical equation, the reactants are located on the left and the products are located on the right. 15. What are the two types of chemical equations? - Ans .The two types of chemical equations are word and symbol equations. 16. What is the balanced symbol equation for the reaction between hydrochloric acid and sodium hydroxide? - Ans .H2SO4 + 2NaOH - Na2SO4 + 2H2O 17. Since there are the same number of atoms on each side of the - sign, the law of conservation of mass has been obeyed (mass has been conserved - no atoms have been created or destroyed). Thus, total mass of the reactants is equal to the total mass of the products. 18. What is a mixture? - Ans .A combination of two or more substances that are not chemically combined. 19. What is the difference between mixtures and compounds? - Ans .In mixtures, the different elements have not been chemically combined. Therefore, in mixtures, the properties are representative of the properties of the individual elements. 20. However, in compounds, the different elements have been chemically combined. Therefore, in compounds, the properties are us