9th Grade Chemistry Common Exam 2 2024-2025 PDF

2024-2025 FIRST SEMESTER GRADE 9 CHEMISTRY - COMMON EXAM 2 THEME-1: INTERACTIONS FROM ATOM TO PERIODIC TABLE Atomic Models (Dalton Atomic Model, Thomson Atomic e Model, Rutherford Atomic Model) -Pearson Book Page 142: Dalton Atomic Theory solid-sphere model ös 1. All matter is...

2024-2025 FIRST SEMESTER GRADE 9 CHEMISTRY - COMMON EXAM 2 THEME-1: INTERACTIONS FROM ATOM TO PERIODIC TABLE Atomic Models (Dalton Atomic Model, Thomson Atomic e Model, Rutherford Atomic Model) -Pearson Book Page 142: Dalton Atomic Theory solid-sphere model ös 1. All matter is made up of tiny particles called atoms. 2. All atoms of a given element are similar to one another and different from atoms of other elements 3. Atoms of two or more different elements combine to form compounds. A particular compound is always made up of the same kinds of atoms and always has the same number of each kind of atom. → definite proportion lK 4. A chemical reaction involves the rearrangement, separation, or combination of atoms. Atoms are neither created nor destroyed during a chemical reaction. Limitation: There is not any subatomic particle. -Pearson Book Page 143: Thomson atomic Model, plum-pudding model → protons and electrons scattered throughout the atom tü Be Electrons were found to be much smaller than the atom and to have extremely small masses. Because atoms are neutral, scientists soon discovered that atoms contained positively charged particles called protons that were much heavier than the electrons. Cathode ray tube exp. Thompson applied electricity to a glass tube, which produced streams of small particles called cathode rays. Because these rays were attracted to a positively charged electrode, Thompson realised that the particles in the rays must be negatively charged. 1 -Pearson Book Page 143-144: Rutherford Atomic Theory, Rutherford realised that the protons must be contained in a small, positively charged region at the centre of the atom, which he called the nucleus. Limitation: fails to explain the positions and movements of the electrons in the atom, cannot answer the question of why electrons do not fall into the nucleus. Gold Foil exp. The particles that came near the dense, positive centre deflected. e (Scientists knew that the nucleus was heavier than the mass of the protons, so they looked for another subatomic particle. Eventually, ös Chadwick discovered neutrons.) Discoveries of subatomic particles Proton, electron, neutron -In class activity Google Classroom Document Part-I Electron: Cathode rays - Thompson lK Proton: Thompson Neutron: Neutral particles - Rutherford, Neutron - Chadwich Structure of Atom -Pearson Book Page 146: Atomic number, mass number Mass number = proton + neutron (Neutral atom) → proton = electron tü -Pearson Book Page 149: Nuclear notation of atom Be + charge → gives e- (cation) - charge → gains e- (anion) 2 Bohr Atomic Model -Pearson Book Page 163: Electromagnetic and Atomic Spectrum Electromagnetic Spectrum: the arrangement of different types of electromagnetic radiation from longest wavelength to shortest wavelength e ös As the wavelength decreases, the frequency and the energy increases. As the wavelength increases, the frequency and the energy decreases. Energy is directly related to frequency. (Energy and frequency) are inversely related to wavelength lK Atomic Spectrum: When the light from the Sun or a light bulb is passed through a prism or raindrops, it produces a continuous spectrum, like a rainbow. When elements are heated, they also produce light. When the light emitted from heated elements is passed through a prism,, it does not produce a continuous spectrum. Instead, an atomic spectrum is produced that consists of different colours separated by dark areas. tü Only certain wavelengths of light are produced when an element is heated, so every element has a unique atomic spectrum. Be 3 -Bohr Atomic Model Google Classroom Document 1. Only orbits of certain radii, corresponding to certain specific energies, are permitted for the electron in a hydrogen atom. 2. An electron in a permitted orbit is in an “allowed” energy state. An electron in an allowed e energy state does not radiate energy and, therefore, does not spiral into the nucleus. 3. Energy is emitted or absorbed by the electron only as the electron changes from one allowed energy state to another. ös Ground state: The lowest-energy state Excited state: When the electron is in a higher-energy state lK -Task#5 Atomic Theories Timeline tü 1. Dalton - solid sphere model 2. Thompson - plum pudding model 3. Rutherford - nucleus 4. Bohr - electrons movement and position (orbit) Be Modern Atomic Theory (Quantum Atomic Theory) - Pearson Book Page 166: Electron Energy Levels n=1, n=2, n=3, … Electron changes to a; higher energy level → absorbs energy equal to the difference in energy levels, lower energy level → emits energy equal to the difference between energy levels 4 - Pearson Book Page 168-173: Sublevels and Orbitals e s