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Learn about atomic numbers, mass numbers, and isotopes to understand how elements differ in terms of protons, neutrons, and electrons. Explore the periodic table and grasp the significance of isotopes in chemistry.
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Distinguishing AmongAtoms CN#10 • Just as apples come in different varieties, a chemical element can come in different “varieties” called isotopes.
4.3 Atomic Number • Atomic Number • What makes one element different from another?
4.3 Atomic Number • Elements are different because they contain different numbers of protons. • The atomic number of an element is the number of protons in an atom. It is also the number of electrons.
for Conceptual Problem 4.1 Problem Solving 4.15 Solve Problem 15 with the help of an interactive guided tutorial.
4.3 Mass Number • Mass Number • How do you find the mass number of an atom?
4.3 Mass Number • The mass number is the total number of protons and neutrons in an atom. • Mass number = protons + neutrons Neutrons = mass number - protons
4.3 Atomic Number
for Sample Problem 4.1 Problem Solving 4.17 Solve Problem 17 with the help of an interactive guided tutorial.
4.3 Isotopes • Isotopes • How do isotopes of an element differ?
4.3 Isotopes • Isotopes are atoms that have the same number of protons but different numbers of neutrons. • Because isotopes of an element have different numbers of neutrons, they also have different mass numbers.
4.3 Isotopes • Despite these differences, isotopes are chemically alike because they have identical numbers of protons and electrons.
for Conceptual Problem 4.2 Problem Solving 4.20 Solve Problem 20 with the help of an interactive guided tutorial.
4.3 The Periodic Table—A Preview • The Periodic Table—A Preview • Why is a periodic table useful?
4.3 The Periodic Table—A Preview • A periodic table is an arrangement of elements in which the elements are separated into groups based on a set of repeating properties. • A periodic table allows you to easily compare the properties of one element (or a group of elements) to another element (or group of elements).
4.3 The Periodic Table—A Preview • The Periodic Table
4.3 The Periodic Table—A Preview • Each horizontal row of the periodic table is called a period. • Within a given period, the properties of the elements vary as you move across it from element to element.
4.3 The Periodic Table—A Preview • A Period
4.3 The Periodic Table—A Preview • Each vertical column of the periodic table is called a group, or family. • Elements within a group have similar chemical and physical properties.
4.3 The Periodic Table—A Preview • A Group or Family
H B Si Ge As Sb Te Po At
4.3 Section Quiz • 4.3.
4.3 Section Quiz • 1. Isotopes of an element have • the same mass number. • different atomic numbers. • the same number of protons but different numbers of neutrons. • the same number of protons but different numbers of electrons.
4.3 Section Quiz • 2. How many neutrons are in sulfur-33? • 16 neutrons • 33 neutrons • 17 neutrons • 32.06 neutrons
4.3 Section Quiz • 3. If sulfur contained 90.0% sulfur-32 and 10.0% sulfur-34, its atomic mass would be • 32.2 amu. • 32.4 amu. • 33.0 amu. • 35.4 amu.
