1. Elements and Symbols 1 letter symbols 1 Capital letter
Element – Pure substance that can not be broken down into simpler substances by a chemical reaction
1 letter symbols
C = Carbon
N = Nitrogen
O = Oxygen
1 Capital letter
2 letter symbols
Cl = Chlorine
Ba = Barium
Au = Gold
1 Capital and 1 lower case letter

3. Compound
Pure substance formed by chemically combining two or more elements
H element + O element can make H2O compound
CO2, HCl, C3H8
Atom smallest unit of an element
Molecule smallest unit of a compound

4. Atom: basic unit of matter
Smallest unit of matter that individually retains the chemical characteristics of an element
Consists of a dense positively charged central region, called a nucleus, surrounded by a negatively charged cloud
Contains three types of subatomic particles:
Proton
Neutron
Electron

5. The Proton Charge = + 1.602×10−19 C Called “+1” for clarity
Located in nucleus of atom
Mass = x 10–24 g
Approx. 1 unified atomic mass unit (u)
1 amu = 1.66 x 10–24 g

6. The Neutron No charge (0 C) Located in nucleus Mass = 1.675 x 10–24 g
Approx. = 1 amu

7. The Electron Charge = –1.602 x 10–19 C Called “–1”
Located outside nucleus in an e- “cloud”
Mass = x 10-28g
Approx. = 0 amu

8. Recap What are the three subatomic particles?
Where are they located in the atom?
What are their weights in atomic mass units
What are their charges?

10. Dmitri Mendeleev (1834-1907) Russian chemist
Arranged elements in horizontal rows in order of increasing atomic weight
Started new rows in order to make columns of chemicals with similar characteristics
Left spaces open for elements yet to be discovered

13. Classification of the Periodic Table
Classification by Physical Properties

14. Metals Shiny Conduct electricity Ductile Can be drawn through wires
Malleable (Shapeable)
High M.P. & B.P
room temp
Except Hg

15. Non-Metals Don’t tend to conduct well Not usually ductile
Tend to be brittle
Low M.P. & B.P.
Many are gases at r.t.

16. Metalloids
Have chemical characteristics in between those of metals and non-metals
Includes elements: B (Boron), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), Astatine (At)

17. Classification by Chemical Properties

18. Alkali Metals Group 1 (1A) Li, Na, K etc. Soft, shiny metals
Conduct heat and electricity
React violently with H2O
Form H2(g) and (basic) solutions

19. Akali(ne) Earth Metals
Group 2 (2A)
Be, Mg, Ca etc.
Not as reactive as Alkali Metals, but still quite reactive
Tend to make basic solutions when placed in water

20. Transition Metals Groups 3B-8B Tend to have high densities and B.P.
All are metals
Often used for electrical conduction
Often have vivid colors when in solution
Used for pigments

21. Colors of Transition Metal Compounds
Nickel
Cobalt
Copper
Zinc
Iron

22. Lanthanides Elements 57-71 Lanthanum (La) to Lutetium (Lu)
Commonly used in lasers
Can deflect UV and infrared rays

23. Actinides/Actinoids Elements 89-103 Actinium (Ac) to Lawrencium (Lr)
Only Actinium, Thorium (Th), and Uranium (U) occur naturally
Others created by neutron bombardment
Radioactive

24. Groups 3A – 6A No common name
Boundary between metals and non-metals occurs here
Contains the metalloids
Contain elements abundant in earth’s crust, atmosphere, and living things
C, N, O, Si

25. Halogens Group 7A Very reactive with many compounds
F, Cl, Br, I, At
Very reactive with many compounds
Like to form diatomic molecules
F2, Cl2, Br2,

26. Noble Gases Group 8A He, Ne, Ar, Kr, Xe, Rn Very unreactive
Don’t like to bond to other molecules
Generally not abundant

27. Problems Write down an element from each of the groups
1. Noble Gas (example-- He aka Helium)
2. Lathanide
3. Alkali metals
4.Halogens
5. Actinides
6. Alkaline metals
7. Element that is abundant in living organisms
Period and group

29. -- Also number of protons
Atomic number
-- Also number of protons
-- Usually the number of electrons as well
Atomic symbol
-- 1 or 2 letter symbol
Average atomic weight or
Approximate Mass number
-- Also number of protons + number of neutrons

31. Can also represent by omitting atomic number (Z) since it is implied by the element
Which atom does the picture below represent?

32. Identify number of protons, the mass number, and number of neutrons for the following elements.

33. Isotopes Atoms of the same element that have different atomic masses
Same number of protons
Different # of neutrons
Percent Abundance - amount of each isotope that occurs naturally

34. Average atomic mass
Weighted average of the mass of naturally occurring isotopes of a particular element reported in atomic mass units
Zi = mass number of smallest isotope
% abd = percent abundance
[Zi(% abd) + Zi+1(% abd) + Zi+2(% abd) + ……]
Example-- [20(0.9092) + 21(0.0026) +22(0.0882)] = amu ~ amu

35. Problems
Lithium has two natural isotopes, 6Li and 7Li, which have percent abundances of 7.5% and 92.5% respectively. What is the average atomic mass of Lithium?

36. Using the percent abundances below, calculate the average atomic mass for Carbon
Antimony (Sb) has two stable isotopes, 121Sb and 123Sb with masses of u and u, respectively. Calculate the percent abundances of these two isotopes

37. Atomic Orbitals and Electron Configurations

38. The shells are numbered n = 1, 2, 3, etc.
2.5 Electronic Structure
An electron is confined to a specific region around the nucleus, giving it a particular energy.
The regions occupied by electrons are called
principal energy levels or shells (n).
The shells are numbered n = 1, 2, 3, etc.
Electrons in lower numbered shells are closer to
the nucleus and are lower in energy.
Electrons in higher numbered shells are further
from the nucleus and are higher in energy.

39. 2.5 Electronic Structure
Shells are divided into subshells, identified by the letters s, p, d, and f.
The subshells consist of orbitals.
An orbital is a region of space where the probability of finding an electron is high.
Each orbital can hold two electrons.
Subshell
Number of Orbitals s 1
increasing
energy p 3 d 5 f 7

40. S orbitals
Spherical shape
Lowest energy of the orbitals

41. P Orbitals Higher energy than s orbitals Dumb bell shaped Come in 3’s
px, py, pz

42. D Orbitals Higher energy than s and p orbitals
Double dumb bell shape or single dumb bell with a donut
Come in 5’s
dxy, dxz, dyz, dx2-y2, dz2

43. F Orbitals
Higher energy than s, p, and d
Come in 7’s

45. How do we know where our electrons are?
Electrons will seek the lowest E orbital available first

47. Hydrogen Helium Lithium? 1
Pauli Exclusion Principle: orbitals may hold up to two electrons. The electrons must be of opposite spin

48. Hund’s Rule: electrons pair only after each orbital of equal energy is occupied by a single electron

49. Problems Determine the electron configurations for the following atomsNa Mg Al S Fe W

50. Noble Gas Abbreviation
The electron configuration of the noble gas that precedes the element in question is represented by the noble gas’ bracketed symbol
Example: C = 1s22s22p2 = [He] 2s22p2
Write the electron configurations for Vanadium and Bismuth

51. Valence Electrons Electrons in the outermost(valence) shell
The shell with the highest number
C = 1s22s22p is highest number
count up electrons in all the valence orbitals
2 electrons in the 2s orbital and 2 electrons in the 2p orbital = 4 valence electrons
P = 1s22s22p63s23p is highest number
2 + 3 = 5 valence electrons
Using the Noble gas abbreviation can help

52. Electron dot symbols Valence electrons represented with dots
Dots are placed on four sides of the element symbol
Up to 2 dots max per side, must fill up all sides before pairing up dots

53. Problems
Determine valence electrons for the following elements and draw the electron dot symbol for each H Li Si Br Ar Ti

54. Periodic Trends Atomic number
increases going to the right and going down
Atomic size (how big the atom is)
increases going to the left and going down
Ionization energy (energy required to remove a valence electron)
increases going to the right and going up

55. Chapter 2 Review Element symbols
Inside the atom. Proton, neutron, and electron. Charge, mass, location.
Periodic Table Bonanza!! Being familiar with the table and how to use it.
Metals, metalloids, non metals. Properties and which elements are from which class.
Group/families of elements. Alkali metals, Alkaline metals, transition metals, Halogens, Lanthanides, etc.
Atomic number and Mass number. Recognizing how many protons electrons and neutrons in an given isotope.
Isotopes percent abundance. Calculating average atomic mass.
Atomic orbitals. s, p, d, f orbitals, different shapes and energies.
Electron configurations. Pauli exclusion principle, Hunds rule, noble gas, abbreviation.
Valence electrons and Electron dot structure
Periodic trends