Atomic and Mass Numbers

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1 Chapter 2 Lesson 2 Atomic and Mass Numbers Attendance link: 1

2 Expectations Required Class Connects Tuesday, Wednesday, Thursday 10:30 11:30 am Be active and participate in class. Be respectful to your classmates Be positive in the chat box and use it correctly Have a working microphone! You will need it during the lessons and break out rooms. If you have a question, please place it in the chat box and repost it if I don t see it. LecturePLUS Timberlake 2

3 Objectives Define atomic number. Compare atomic number with the atomic mass of an element. Explain how an isotope of an element has the same number of protons but a different number of neutrons in the nucleus. Recognize that isotopes of an element typically have many similar characteristics. 3

4 Atomic Theory Atoms are building blocks of elements Similar atoms in each element Different from atoms of other elements 4

5 Atomic Particles

6 Location of Atomic Particles electrons nucleus protons neutrons 6

7 Atomic Number 7

8 Atomic Number Atomic Number of an element is the number of protons in the nucleus of each atom of that element. Element # of protons Atomic # Carbon 6 6 Phosphorus Gold 79 79

element All atoms of an element have the same number of

9 The Atomic Number of an element is also the number of electrons found in a neutral (no charge) atom of that element All atoms of an element have the same number of protons and electrons 11 protons Sodium 11 Na 11 electrons

10 Atomic Mass on the Periodic Table Atomic Number 11 Symbol Na Mass # Atomic Mass 23

11 Atomic Number and Atomic Mass Element name Symbol boron 5 B Atomic number Atomic mass

12 Mass Number Mass number is the number of protons and neutrons in the nucleus of an isotope. Mass number is determined by rounding the atomic mass to the nearest whole # Arsenic Phosphorus Mass # = p + + n o

13 Learning Check State the number of protons for atoms of each of the following: 1. Nitrogen A) 5 protons B) 7 protons C) 14 protons 2. Sulfur A) 32 protons B) 16 protons C) 6 protons 3. Barium A) 137 protons B) 81 protons C) 56 protons N 7; S 16; Ba 56 13

14 14

15 Summary: Atomic Number = # protons = # electrons (neutral atom) Mass # (atomic mass rounded) = # protons + # neutrons Neutron # = Mass # - Proton #

16 Mass Number Counts the number of protons and neutrons in an atom 16

17 Atomic Symbols Show the mass number and atomic number Give the symbol of the element mass number atomic number Na sodium-23 17

18 Number of Electrons An atom is neutral The net charge is zero Number of protons = Number of electrons Atomic number = Number of electrons 18

19 Element Name Atomic Number Number of Protons Number of Neutrons Mass Number carbon 12 Oxygen hydrogen 1 Carbon hydrogen nitrogen 14

20 Atomic Mass Atomic mass is the weighted average mass of all the atomic masses of the isotopes of that atom. 20

21 Isotopes Atoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different mass numbers Isotopes of Chlorine 35 Cl 37 Cl Chlorine - 35 Chlorine - 37

22 Isotopes Despite these differences, isotopes are chemically alike because they have identical numbers of protons and electrons.

23 Isotopes Isotope Protons Electrons Neutrons Nucleus Hydrogen 1 (protium) Hydrogen-2 (deuterium) Hydrogen-3 (tritium) 1 1 2

24 Learning Check Naturally occurring carbon consists of three isotopes, 12 C, 13 C, and 14 C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12 C 13 C 14 C #p #n #e 24

25 Learning Check Naturally occurring carbon consists of three isotopes, 12 C, 13 C, and 14 C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12 C 13 C 14 C #p #n #e

26 Learning Check An atom of zinc has a mass number of Number of protons in the zinc atom A) 30 B) 35 C) Number of neutrons in the zinc atom A) 30 B) 35 C) What is the mass number of a zinc isotope with 37 neutrons? A) 37 B) 65 C) 67 26

27 Solution An atom of zinc has a mass number of Number of protons in the zinc atom A) Number of neutrons in the zinc atom B) What is the mass number of a zinc isotope with 37 neutrons? C) 67 27

28 What s the point of Isotopes You can tell how old something is Radiocarbon Dating Unstable isotopes can break apart rather quickly. When they break up, these isotopes maybe transformed into smaller elements. Use as markers in research Follow a certain molecule, atom

29 ICW: Will be working in breakout rooms. Have a Periodic Table out to help you. Everyone submits their own link. LecturePLUS Timberlake 29

30 Fill in the missing numbers and words (the pink #s are place holders). LecturePLUS Timberlake 30

31 Practice For each isotope, give the number of protons, electrons, and neutrons: C-14 p e n Na-21 p e n Be-8 p e n S-31 p e n

32 Practice For each isotope, give the number of protons, electrons, and neutrons: C-14 6 p 6 e 8 n Na p 11 e 10 n Be-8 4 p 4 e 4 n S p 16 e 15 n

33 Questions? Make sure you save the Whiteboard! File, save, whiteboard, all pages, make sure you save it as a PDF. Interactive Periodic Table 33

Unit 4: The Atom, Atomic Number, Mass Number, And Isotopes

#5 PPT APE MAN AND ISOTOPES! Unit 4: The Atom, Atomic Number, Mass Number, And Isotopes LecturePLUS Timberlake 1 Atomic Theory Atoms are building blocks of elements Similar atoms in each element Different