Chapter Assessment Answer Key Chemistry: Matter and Change T167 4 CHAPTER ASSESSMENT Date alpha radiation Dalton’s atomic theory radiation radioactivity Chapter Assessment particles involved in a reaction. Chemistry: Matter and Change • Chapter 4 nucleus. A nuclear equation shows the atomic number and mass number of the 19 Both concern changes in atoms. A nuclear reaction involves a change in an atom’s 15. nuclear reaction, nuclear equation atom. in the nucleus of a given atom.
INTRODUCTION TO NUCLEAR REACTION: The main features of nuclear reactions include radioactive decay, nuclear fission and nuclear fusion. Radioactive decay: Energy is released in a radioactive decay in the form of the kinetic energy of the particle emitted (α and β), the kinetic energy of the daughter nucleus and the energy of the gamma-ray photon that may accompany the decay. The energy involved may be calculated by finding the mass defect of the reaction. The energy released is the energy equivalent of the mass defect of the reaction. Nuclear fission: Nuclear fission is the process in which a large nucleus breaks into two smaller nuclei that are almost equal in mass.
The arrangement of particles in an atom Protons and neutrons make up the main, dense, central nucleus in the centre of the atom. This is surrounded by electrons “orbiting” the main nucleus. The electron are in shells depending on their energy levels, as the most energetic are on the outer shells, because they need more energy to travel around a bigger “orbit” of the nucleus. These shells are full when a certain amount of atoms are in the shell; 2 in the first shell, 8 in the next shell, 8 in the third shell and so on. When the shells are full, the atom is unreactive.
Describe the differences between protons and electrons The difference between protons and electrons is that protons are positively charged and that elections are negatively charged. Another difference is that protons are in the nucleus and electrons circle the nucleus in shells outside the nucleus. What is the difference between the mass number and the relative atomic mass of an element? The difference between the mass number and the atomic mass is that the mass number is the number of protons and neutrons in the nucleus and the relative atomic mass is the mass of an atom. Distinguish between an element and a compound with 2 examples for each An element is a substance that cannot be broken down into any simpler substances.
David Kemp OCR Chemistry A Unit 1: F321 Atomic Structure (a) describe protons, neutrons and electrons in terms of relative charge and relative mass; Proton +1 1 Neutron 0 1 Electron -1 1/2000 Relative Charge Relative Mass (b) describe the distribution of mass and charge Within an atom; Positively charged Nucleus containing most of the mass, surrounded by atomic shells with orbiting electrons of negative charge and negligible mass. (c) describe the contribution of protons and neutrons to the nucleus of an atom, in terms of atomic (proton) number and mass (nucleon) number. The atomic number of the nucleus, also the proton number, shows the number of protons in the nucleus. It also defines the element. The number of neutrons added to the number of protons is the nucleon number or mass number.
Astronomy 10 Chapter 11 1. Both used to be normal stars but the white dwarf ran out of hydrogen, they are both subjected to gravitational theories. A Neutron star is a fluid of neutrons, as hot at its surface as the inside of the sun and has a greater magnetic field. 3. Because its density is so high, neutrons spin in the same way that electrons do so must obey the Pauli Exclusion Principle.
Although some subatomic particles have a greater mass than some atoms. Subatomic particles are made of quarks such as a proton which is made of two up quarks and one down quark. The atom is a basic unit of matter that consists of a dense nucleus surrounded by negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons. The electrons of an atom are bound to the nucleus by the electromagnetic force.
OCR B CHEMISTRY F331 (Unit 1) Revision Guide 2014 Formulae, equations and amount of substance | Key Terms (a). * Atomic Number: Atomic number is the number of protons in the nucleus. * Mass Number: Mass number is defined as the sum of the numbers of protons and neutrons in the atom’s nucleus. * Isotopes: Atoms with the same number of protons but different number of neutrons are called isotopes; they therefore have different masses. * Avogadro’s constant: The number of toms per mole is called the Avogadro’s constant.
Concept Explorations 8.29. Periodic Properties I A hypothetical element, X, has the following ionization energy values: First ionization energy: 900 kJ/mol Second ionization energy: 1750 kJ/mol Third ionization energy: 14,900 kJ/mol Fourth ionization energy: 21,000 kJ/mol Another element, Y, has the following ionization energy values: First ionization energy: 1200 kJ/mol Second ionization energy: 2500 kJ/mol Third ionization energy: 19,900 kJ/mol Fourth ionization energy: 26,000 kJ/mol * a. To what family of the periodic table would element X be most likely to belong? Explain? * X belongs to Group 2 of the periodic table because it has a low first and second ionization energy, however, a higher second and third.
Electromagnetism Everything is made out of atoms. Atoms consist of a nucleus (containing neutrons and protons) and a cloud of electrons surrounding the nucleus. Protons are positively charged and electrons are negatively charged. If an object has more protons than neutrons, then it is negatively charged. If an object has more electrons than protons, then it is positively charged.