Grade 9 Chemistry

Grade 9 Chemistry 1. Define Atom. - Answer: An atom is the fundamental and smallest unit of a chemical element, composed of three subatomic particles: protons, neutrons, and electrons. 2. Explain Atomic Radius. - Answer: Atomic radius refers to the average distance from the center of an atom's nucleus to its electrons in the outermost orbital. 3. What is Boiling Point? - Answer: Boiling point is the temperature at which a liquid changes to vapor, such as water boiling at 100°C under standard conditions. 4. Describe Binary Compound. - Answer: A binary compound consists of two different chemical elements, often forming ionic bonds. 5. Define Chemical Change. - Answer: Chemical change involves the irreversible rearrangement of atoms in one or more substances, resulting in the formation of new substances with altered chemical properties. For example, the rusting of iron is a chemical change. 6. Explain Chemical Property. - Answer: A chemical property is a characteristic of a substance that becomes evident during chemical reactions, involving changes in composition or identity. For instance, combustibility, which determines if a material can catch fire and burn, is a critical chemical property. 7. What does Combustibility refer to? - Answer: Combustibility describes the ability of a substance to ignite and burn, such as the highly flammable nature of gasoline vapor. 8. Define Compound. - Answer: A compound is a pure substance composed of two or more elements chemically bonded together, resulting in unique physical and chemical properties. For example, salt (sodium chloride) is a compound. 9. Describe Conductivity. - Answer: Conductivity is the property of a material to conduct heat, electricity, or sound. Electrical conductivity, for example, is essential for the efficient transmission of electricity through wiring.