Unit 2 ( Isotopes Problem Set 2-2 1. Which of the following are isotopes of element X, with atomic number of 9: [pic],[pic],[pic], and [pic]. 2. For each of the following isotopes, write the nuclear symbols: a. Cu-63, Cu – 65 b. C-12, C-14 c. Mg-24, Mg-25, Mg-26 d. Ne-20, Ne-21, Ne-22 3. Verify that the atomic mass of magnesium is 24.31 amu, given the following information: [pic], mass = 23.985042 amu; percent abundance = 78.99% [pic], mass = 24.985837 amu; percent abundance = 10.00% [pic], mass = 25.982593 amu; percent abundance = 11.01% 4.
A. 1.99 x 10-25 B. 9.55 x 10-25 C. 6.62 x 1016 D. 1.51 x 10-17 E. 1.51 x 10-26 4. Of the following transitions in the Bohr hydrogen atom, the __________ transition results in the emission of the highest-energy photon. A. n = 3 n
Aluminium and potassium 7) A certain particle was found to contain sixteen protons and eighteen electrons. a. What element must it be? State your reasoning A sulphur ion because it has 16 protons and 16 neutrons, it needs two extra electrons to become and ion. b.
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.
Final exam chem 2014 Multiple Choice Identify the choice that best completes the statement or answers the question. ____ 1. A central concept of the kinetic theory, one of the “big ideas” of chemistry, is the belief that a.|for every reaction there is an equal and opposite reaction.| b.|chemical reactions involve processes in which reactants produce products.| c.|the particles in matter are in a state of constant motion.| d.|every chemical process uses or produces energy, often in the form of heat.| ____ 2. In a chemical reaction, the type of products obtained is largely determined by which part of the reacting chemicals? a.|protons| b.|electrons| c.|neutrons| d.|nuclei| ____ 3.
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.
E) chlorine gains a proton from sodium. 10) The atomic number of chlorine is 17. The atomic number of magnesium is 12. What is the formula for magnesium chloride? A) MgCl B) MgCl2 C) Mg2Cl D)
HSC Chemistry Assessment task 1 Nuclear Chemistry Research report 1. Distinguish between stable and radioactive isotopes and describe the conditions which a nucleus is unstable. To understand if an element is stable we first must understand what stability is. The stability of the nucleus is directly related to the strength of the forces that hold the nuclear particles together. These protons and neutrons of the nucleus are called nucleons.
Your friend says that what makes one element distinct from another is the number of electrons about the atomic nucleus. Do you agree wholeheartedly, partially, or not at all? Explained • NO • What makes one element distinct from another is the number of protons in the nucleus. Hydrogen has 1, gold has 79, uranium has 92, etc. Not electrons.
(1 point for each molecule) The central atom is C. 2. How many atoms are bonded to the central atom? (1 point for each molecule) There are two atoms bonded to the central atom. 3. How many lone pairs of electrons are on the central atom?