Edexcel Chemistry 2023 Exam Questions And Complete Solutions

Edexcel Chemistry 2023 Exam Questions And Complete Solutions What are the three ideas in John Dalton's theory about the atom? - ANSWER - Atoms cannot be created, divided or destroyed. - Atoms of the same element are exactly the same and atoms of different elements are different. - Atoms join with other atoms to make new substances What discovery caused the original Dalton model of an atom to change? - ANSWER The discovery of subatomic particles. How did JJ Thomson discover the electron? - ANSWER Thomson experimented with a cathode ray tube. The beam moved towards the positively charged plate so he knew that the particles must have a negative charge. Describe the atomic model proposed by JJ Thomson - ANSWER Plum pudding model. Negatively charged electrons scattered through a positively charged material. What did Ernest Rutherford discover from his gold foil experiment? - ANSWER He shot a beam of positively charged particles at sheet of gold foil. - Most of the particles passed straight through suggesting that atoms were mostly empty space. - A few particles were deflected and a few bounced directly back showing that there must be a tiny, dense and positively-charged nucleus. Describe Rutherford's new model of the atom - ANSWER - Mass is concentrated in the central nucleus. - Mostly empty space. - Electrons travel in random paths around the nucleus. Describe the structure of an atom - ANSWER Small central nucleus made up of protons and neutrons. Electrons orbit (move around) the nucleus in shells. What is the radius of the nucleus? How large is it compared to the radius atom? - ANSWER The radius of the nucleus is 1x10-14 m. This is 1/10000 of the atomic radius. What are the relative masses of protons, neutrons and electrons? - ANSWER Proton: 1 Neutron: 1 Electron: 1/1836 What are the relative charges of protons, neutrons and electrons? - ANSWER Proton: +1 Neutron: 0 Electron: -1 Why do atoms contain equal numbers of protons and electrons? - ANSWER Atoms are stable with no overall charge.