Chapter 2 - Atoms and the Atomic Theory - Exercises - Self-Assessment Exercises - Page 66: 96

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(a) Cathode rays are streams of electrons that are emitted from a cathode when an electric potential difference is applied across a vacuum. X-rays are high-energy electromagnetic radiation that is produced when electrons strike a target material. Cathode rays are negatively charged particles, while X-rays have no charge (b) The nucleus of an atom contains the subatomic particles protons and neutrons. Neutrons are uncharged, whereas protons have a positive charge. An atom's atomic number and subsequent identification as a particular element are determined by the quantity of protons in the nucleus. Several isotopes of the same element might exist depending on the amount of neutrons present in their atoms. (c) Nuclear charge refers to the positive charge of an atomic nucleus, which is equal to the number of protons in the nucleus. Ionic charge refers to the electric charge of an ion, which can be positive or negative and is caused by the gain or loss of electrons. Nuclear charge is a fundamental property of an element, while ionic charge depends on the chemical context in which the ion is found. (c) Nuclear charge describes an atomic nucleus' positive charge, which is determined by the number of protons present. The electric charge of an ion, which can be positive or negative and is brought on by the gain or loss of electrons, is referred to as having an ionic charge. Ionic charge is dependent on the chemical environment in which the ion is present, whereas nuclear charge is a fundamental feature of an element. (e) Metals are elements that are generally shiny, ductile, malleable, and good conductors of heat and electricity. Nonmetals are elements that are generally dull, brittle, and poor conductors of heat and electricity. f) The Avogadro constant is the number of particles (usually atoms or molecules) in one mole of a substance, equal to 6.022 x 10^23 particles. The mole is a unit of measurement used in chemistry to express the amount of a substance. One mole of a substance is defined as the amount of the substance that contains the same number of particles as there are in 12 grams of carbon-12.