1 Which scientist is credited with the discovery of electrons by experimenting with Cathode Ray Tubes?

Atomic Structure Notes

3 Atomic Structure Subatomic particles include ________, _________ and _________. protons neutrons electrons ________ and _________ are inside the ________ Protonsneutrons nucleus __________ are found __________ the nucleus Electrons outside Atoms are made up of __________ _________. subatomicparticles

4 Subatomic Particles Protons have a _________ charge and a mass of ________. Neutrons have a _________ charge and a mass of _________. Electrons have a _________ charge and a mass that is so ______ that we consider electrons to have ____ mass! + 1 AMU neutral 1 AMU - small “NO” 1 AMU = Atomic Mass Unit

5 Number of Protons Elements in the Periodic Table are organized by ________ ________. Atomic number The atomic number is the same as the number of ________. protons Every element has a _________ number of protons, and therefore a ________ atomic number. different

6 Atomic Number = # protons

7 Number of Electrons In a _________ atom, the number of _________ always equals the number of __________. neutral protons electrons #p = #e

8 Electron Practice Find the number of protons and electrons in the following atoms: SymbolProtonsElectrons Mg O Au Ti

9 Atomic Mass Proton = ________ amu 1 An atom’s mass is the sum of its parts Electron = ________ amu Neutron = ________ amu 1 0 Since the electron has practically no mass we don’t count it in the mass of the atom

10 Atomic Mass You can find the mass of an atom from the __________ _______ Periodic For us, that mass is the sum of the __________ and __________. Protons Table Neutrons Fluorine has - __________ protons __________ neutrons 9 19

11 Atomic Mass = # protons + # neutrons

12 Number of Neutrons To get the number of neutrons, get the atomic mass from the _________ ______ and subtract from that the number of ________. Periodic #neutrons = Atomic Mass - #p Table protons

13 Neutron Practice Find the number of p, n and e in the following atoms: SymbolProtonsNeutronsElectrons Na B H C

14

15 Atomic Structure wkst Textbook Packet

16 How many neutrons does a lead atom have?

17 Qz: Atomic Structure

18 Element Symbols Every element has a _________ on the Periodic Table. symbol The symbol is either 1 or 2 letters, where the first is always a _________ letter, and the second is always a _______ letter… CAPITAL small H He C Ca

19 Element Notation Element symbols contain the atomic number, mass number and element symbol. J Mass number Atomic number Element symbol

20 Element Notation Complete the notation for the following: KAl

21 Atomic Structure wkst Textbook Packet coninued

22 Identify the atom that has 26 neutrons, 22 protons and 22 electrons.

BELL RINGER Draw the electron dot diagrams for Chlorine and Sodium.

BELL RINGER How many electrons does a phosphorus atom have? Neutrons?

BELL RINGER Draw the Bohr diagrams for Lithium and Oxygen.

The Bohr Model The ________ is in the center of the atom and contains both _________ and __________, and the ___________ are found orbiting the nucleus. nucleus protons neutrons electrons Basic Layout

Electron Energy Levels Electrons are found in _______ levels around the nucleus. energy The _______ to the nucleus, the ________ the energy of the electrons. closer lower The _______ from the nucleus, the ________ the energy of the electrons. farther higher

Electron Configuration Electron configuration is the ___________ of electrons outside the nucleus of an atom. arrangement The 1 st energy level holds up to ____ electrons. 8 2 nd level holds up to ___ 3 rd level holds up to ___ 18 2

Electron Configuration You don’t have to memorize this, use the Periodic Table Look under the atomic number and you will see where the electrons will go For Oxygen, there are ___ electrons in the 1 st level and ___ electrons in the 2 nd level. 2 6

How to: Bohr Models Rules 1. Put the number of _______ in the ________ protonsnucleus 2. Put the number of _________ in the ________ neutrons nucleus 3. Put a dot for each electron in the ______ energy level (Max of __ ) and then move on to the second if necessary. 5. Put a dot for each electron in the _______ energy level (Max of __ ) and then move to the third if necessary. first 2 8 second 6. Repeat for the third level if necessary

31 Practice: Bohr Models Draw the Nucleus – make sure it is big enough to write inside Add the protons and neutrons to the nucleus 3p 4n Draw the first energy level and put a dot for each electron on that level (Max of 2) Li Draw the second energy level and put a dot for each electron on that level (Max of 8) Notice the yellow electrons – these are Valence Electrons (e- on the outermost shell)

32 Practice: Bohr Models Draw the Nucleus – make sure it is big enough to write inside Add the protons and neutrons to the nucleus 13p 14n Draw the first energy level and put a dot for each electron on that level (Max of 2) Al Draw the second energy level and put a dot for each electron on that level (Max of 8) Draw the third energy level and put a dot for each electron on that level (Max of 18) Notice the yellow electrons – these are Valence Electrons (e- on the outermost shell)

33 Bohr Diagram wkst

Draw the Bohr diagram for an atom of Aluminum.

What are they? Why are they important? Review: Valence Electrons Electrons on the outermost energy level They are the only electrons involved in chemical reactions How do you know how many an atom has? On the Periodic table, below the atomic number

Electron Dot diagrams, (also called ______ Dot diagrams) show only the _________ electrons in an atom. Lewis valence It includes the ______________ and the _______ of valence electrons. element symbol number Let’s figure out the ‘rules’ for drawing Lewis/Electron Dot Diagrams… Lewis Dot Diagrams

1. The first __ valence electrons go on the _____ side of the element symbol. 2 top HHe Rules - Lewis Dot Diagrams

2. Electrons are added ____ at a time in a _________ direction as seen below. one clockwise J 1 2 Rules - Lewis Dot Diagrams

39 Practice

40 p= n= 9 10 Identify the atom above

Electron Movement

We already learned that electrons are located on specific _______ ______ outside the nucleus The electrons closer to the nucleus have ______ energy and need to _______ energy to get farther away from the nucleus. lower absorb Electron Energy energy levels

Electron Movement When you look on the periodic table, you get the _______ state electron configuration ground If exposed to enough _____ or __________ energy, electrons can _______ energy and jump up an energy level and become ______. heat electrical absorb excited

44 The excited state is __________, and really quickly the electron will _____ back down to where it came from and give off the energy it absorbed. Electron Movement temporary drop

Electrons will release energy as ______. Since each energy level jump has a different _______ of energy, the energy given off will be a different ______ of light. light amount color Energy Released

Normal Light White light is made of ____ the colors of the _________. all spectrum Passing light through a ______ separates the light into individual ________ – each having its own ______________. prism colors wavelength

Bright-Line Spectra Each element gives off different ________ of energy – this produces a unique _______ of ______ and ________ that we call a __________ spectrum. amounts patternlines colors bright-line n = 3 n = 4 n = 2 n = 1

Bright-line Spectra They are formed when atoms ______ (give off) __________. emit energy Each element produces a ________ pattern. unique

49 Unknown Spectra

Flame Test lab

Spectroscopy lab

BELL RINGER Unknown What element is the unknown?

Isotopes Isotopes are atoms of the same ________ that have different numbers of ________ and therefore different ________. element neutrons masses How many neutrons do each of the carbon atoms to the right have?

Isotope Problems Which of the following are isotopes of each other? O 17 8 C 6 O 18 8 N 8 How many protons and neutrons do the following have? Cl 37 6 K 40

55 Practice

Ions Ions have the same number of _______ but a different number of _________. protons electrons This makes an ion a ________ particle, since there aren’t the same number of ________ and _________. charged protonselectrons Not or

Calculating Charge Remember: Electrons are negative! The charge of the ion is always written here If the _____ has more electrons it is _____! Cl -1 If the _____ has more protons it is _____! ion - +

Ion Practice Figure out the electrons for each of the following ions Na +1 S -2 Al +3 F -1

59 Practice

BELL RINGER Draw the dot diagram and Bohr diagram for Si.

BELL RINGER Give the p, n, and e for both isotopes of Cl-35 and Cl-37.

62 Identify the number of p, n, and e in an atom of Fluorine.

BELL RINGER Draw the Bohr diagram for Sulfur.

BELL RINGER How are bright lines produced?

BELL RINGER How can we identify elements based upon flame tests?

BELL RINGER What is the charge and location for all three of the subatomic particles?

BELL RINGER How do we know what elements stars are made of?

Quiz 1.How many valence electrons does Strontium have? 2.What is the symbol for the element iron? 3.Draw the Bohr diagram for Chlorine.

Quiz 4.What is the electron configuration for Arsenic? 5.How many neutrons does Phosphorus have?

BELL RINGER Draw the Bohr diagram and Dot diagram for Boron.

71