1. Ch. 5: Atomic Structure
Standards: Matter consists of atoms that have internal structures that dictate their chemical and physical behavior.
Targets:
State the position of protons, neutrons and electrons in the atom
State the relative masses and relative charges of protons, neutrons and electrons.
Define the terms mass number (A), atomic number (Z) and isotopes of an element.
Deduce the symbol for an isotope given its mass number and atomic number.
Calculate the number of protons, neutrons and electrons in atoms and ions from the mass number, atomic number and charge.
Calculate the relative atomic mass given the abundance and isotopes of an element
State how the periodic table is organized by atomic number, groups, and periods.

2. State the position of protons, neutrons and electrons in the atom
History of Atomic Theory
Democritus (420 BCE)
Greek philosopher; matter composed of small particles-atoms: purely hypothesis, no data
Aristotle ( BCE)
Greek philosopher; matter composed of earth, air, fire, water. This view dominated thought until 17th century
John Dalton ( )
English chemist; was the first to base atomic theory on scientific evidence.

3. State the position of protons, neutrons and electrons in the atom
Dalton’s Atomic Theory
Elements are made of tiny particles called atoms.
All atoms of a given element are identical. The atoms of a given element are different from those of any other element.
Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative number of types of atoms.
Atoms cannot be created, nor divided into smaller particles, nor destroyed in the chemical process. A chemical reaction simply changes the way atoms are grouped together.

4. State the position of protons, neutrons and electrons in the atom
Evidence for sub-atomic particles
1897: J.J. Thomsen: Cathode Ray Tube
Evidence for electrons: Bent a stream of rays originating from the negative electrode (cathode). Stream of particles with mass & negative charge.
1909: Ernest Rutherford: Gold Foil
Evidence for protons & nucleus: Alpha particles deflected passing through gold foil
1932: James Chadwick: Beryllium
Evidence for neutrons: Alpha particles caused beryllium to emit rays that could pass through lead but not be deflected,

5. Atomic Structure Atomic Particles Nucleus: center
State the position of protons, neutrons and electrons in the atom. State the relative masses and relative charges of protons, neutrons and electrons.
Atomic Structure
Nucleus: center
Electron Cloud: outside
(Draw and label a diagram of an atom)
Atomic Particles
*In a neutral atom: # of protons = # of electrons
Particle
Location
Charge
Relative Mass
Proton (p+)
Nucleus
+ (positive)
1 amu
Neutron (no)
0 (no charge)
Electron (e-)
Cloud
- (negative)
0 amu

6. All oxygen atoms have 8 protons in the nucleus
Define the terms mass number (A), atomic number (Z), and isotope of an element
Atomic Number (Z)
The atomic number is the number of protons in the nucleus. It determines the identity of an atom.
All oxygen atoms have 8 protons in the nucleus
All lead atoms have 82 protons in the nucleus
Pg and 8

7. It also tells us the number of electrons in a neutral atom
Define the terms mass number (A), atomic number (Z), and isotope of an element
Atomic Number (Z)
It also tells us the number of electrons in a neutral atom
A neutral sodium atom contains 11 protons and 11 electrons
A neutral bromine atom contains 35 protons and 35 electrons
Pg and 8

8. Find the Atomic Number (Z) for the following:
Define the terms mass number (A), atomic number (Z), and isotope of an element
Find the Atomic Number (Z) for the following:
Nitrogen
Potassium
Iodine
How many protons do the above atoms have?
How many electrons do the above atoms have?

9. Find the Atomic Number (Z) for the following:
Define the terms mass number (A), atomic number (Z), and isotope of an element
Find the Atomic Number (Z) for the following:
Nitrogen: 7
Potassium: 19
Iodine: 53
How many protons do the above atoms have?
How many electrons do the above atoms have?
N: 7, K: 19, I: 53

10. Define the terms mass number (A), atomic number (Z), and isotope of an element
It is not practical to measure the masses of atoms in grams due to their small size.
Scientists devised a measurement called atomic mass units (amu).
Protons have a mass of 1 amu
Neutrons have mass of 1 amu
Electrons have mass of 0 amu.

11. Mass number = # protons + # neutrons
Define the terms mass number (A), atomic number (Z), and isotope of an element
Mass Number (A)
Mass number = # protons + # neutrons
To find neutrons, subtract the atomic number from the mass number
Ex: Sodium Z: 11, A: 23, how many neutrons?
23-11 = 12 neutrons

12. Find the mass number (A) for the following elements:
Define the terms mass number (A), atomic number (Z), and isotope of an element
Find the mass number (A) for the following elements:
Oxygen
Sodium
Arsenic
How many protons do these atoms have?
How many neutrons do these atoms have?
STOP: Practice Here

13. Find the mass number (A) for the following elements:
Define the terms mass number (A), atomic number (Z), and isotope of an element
Find the mass number (A) for the following elements:
Oxygen: 16
Potassium:
Arsenic:
How many protons do these atoms have?
O:8, K:19, As:33
How many neutrons do these atoms have?
O: 8, K: , As:
STOP: Practice Here

14. Define the terms mass number (A), atomic number (Z), and isotope of an element
Atoms of the same element can have different numbers of neutrons, thus they will have different masses.
These are called isotopes of the element.

15. Define the terms mass number (A), atomic number (Z), and isotope of an element
There are three isotopes of hydrogen:
Hydrogen-1 has 1 proton, 1 electron, 0 neutrons
Hydrogen-2 has 1 proton, 1 electron, 1 neutron
Hydrogen-3 has 1 proton, 1 electron, 2 neutrons

16. Deduce the symbol for an isotope given its mass number and atomic number
Names for Isotopes: Name of element – Mass Number
Symbols for Isotopes:
Element Symbol
Mass Number
Atomic Number

17. Deduce the symbol for an isotope given its mass number and atomic number
Consider an atom that has an atomic number (Z) of 29 and a mass number (A) of 63. What is its name and symbol?
atomic number of 29 identifies it as copper
Name:
Symbol:

18. Deduce the symbol for an isotope given its mass number and atomic number
Consider an atom that has an atomic number (Z) of 29 and a mass number (A) of 63. What is its name and symbol?
atomic number of 29 identifies it as copper
Name: Copper-63
Symbol: 63 Cu 29

19. Deduce the symbol for an isotope given its mass number and atomic number
Consider an atom that has an atomic number
Consider an atom that has A=32 and Z=16. What is its name and symbol?
Z=16 identifies it as sulfur
Name:
Symbol:

20. Deduce the symbol for an isotope given its mass number and atomic number
Consider an atom that has A=32 and Z=16. What is its name and symbol?
Z=16 identifies it as sulfur
Name: Sulfur-32
Symbol: 32 S 16

21. Deduce the symbol for an isotope given its mass number and atomic number
Consider an atom that has an atomic number of 74 and a mass number of 185. What is its name and symbol?

22. Deduce the symbol for an isotope given its mass number and atomic number
Consider an atom that has an atomic number of 74 and a mass number of 185. What is its name and symbol?
atomic number of 74 identifies it as tungsten
Name: Tungsten-185
Symbol: 185 W 74

23. Deduce the symbol for an isotope given its mass number and atomic number
Consider an atom that has A=127 and Z=53. What is its name and symbol?

24. Deduce the symbol for an isotope given its mass number and atomic number
CConsider an atom that has A=127 and Z=53. What is its name and symbol?
Z=53 identifies it as iodine
Name: Iodine-127
Symbol: 127 I 53

25. Calculate the number of protons, neutrons, and electrons in atoms and ions from the mass number, atomic number, and charge
Consider the neutral carbon-12 atom. How many protons, neutrons, and electrons are in an atom and what is the name and symbol?
Atomic mass =
Atomic number =
Protons =
Neutrons =
Electrons =
Name is
Symbol is

26. Calculate the number of protons, neutrons, and electrons in atoms and ions from the mass number, atomic number, and charge
Consider the neutral carbon-12 atom. How many protons, neutrons, and electrons are in an atom and what is the name and symbol?
Atomic mass = 12
Atomic number = 6
Protons = 6 (atomic number)
Neutrons = 6 (mass – protons)
Electrons = 6 (neutral atom so same as protons)
Name is Carbon-12
Symbol is 12C 6

27. Calculate the number of protons, neutrons, and electrons in atoms and ions from the mass number, atomic number, and charge
Consider an atom that has 9 protons, 9 electrons, and 10 neutrons. What is its atomic number, atomic mass, name, and symbol? Z= A=
Name:
Symbol:

28. Calculate the number of protons, neutrons, and electrons in atoms and ions from the mass number, atomic number, and charge
Consider an atom that has 9 protons, 9 electrons, and 10 neutrons. What is its atomic number, atomic mass, name, and symbol?
Z=9 (atomic number = # protons)
A=19 (atomic mass = protons + neutrons)
Fluorine-19 (name and mass)
19F (neutral because protons = electrons) 9

29. Calculate the number of protons, neutrons, and electrons in atoms and ions from the mass number, atomic number, and charge
Consider a neutral atom with A=75 and Z=33. How many protons, neutrons, and electrons are in the atom. What is the name and symbol?
Consider a neutral atom with A=77 and Z=33. How many protons, neutrons, and electrons are in the atom. What is the name and symbol?

30. pg 116: Practice problems 9,10,11 pg 117: Practice problems 12,13
Calculate the number of protons, neutrons, and electrons in atoms and ions from the mass number, atomic number, and charge
Consider a neutral atom with A=75 and Z=33. How many protons, neutrons, and electrons are in the atom. What is the name and symbol?
Protons = 33 Neutrons = 42 Electrons = 33
Name: Arsenic-75
Symbol: 75As 33
Consider a neutral atom with A=77 and Z=33. How many protons, neutrons, and electrons are in the atom. What is the name and symbol?
Protons = 33 Neutrons = 44 Electrons = 33
Name: Arsenic-77
Symbol: 77As
pg 116: Practice problems 9,10,11 pg 117: Practice problems 12,13

31. Calculate the number of protons, neutrons, and electrons in atoms and ions from the mass number, atomic number, and charge
Ions are charged particles formed when atoms gain or lose
electrons resulting in unequal numbers of protons and electrons
Cations: Atoms that lose electrons become positively charged
Anions: Atoms that gain electrons become negatively charged

32. Deduce the symbol for an isotope given its mass number and atomic number
Symbols for Ions:
Charge
Mass Number N
Element Symbol
Atomic Number

33. Calculate the number of protons, neutrons, and electrons in atoms and ions from the mass number, atomic number, and charge
How many protons, neutrons, and electrons are in an ion of K-39 that has lost one electron? What is the charge of the ion? What is its symbol?

34. Protons = 19 Neutrons = 20 Electrons = 18
Calculate the number of protons, neutrons, and electrons in atoms and ions from the mass number, atomic number, and charge
How many protons, neutrons, and electrons are in an ion of K-39 that has lost one electron? What is the charge of the ion? What is its symbol?
Name: Potassium-39
Protons = Neutrons = Electrons = 18
Charge = 1+ or +1 Symbol is 39K1+ 19

35. Calculate the relative atomic mass of an element
In nature, most elements occur as a mixture of two or more isotopes. The relative atomic mass is calculated using the percent abundance and mass of each isotope. .

37. Calculate the relative atomic mass of an element
The relative atomic mass of chlorine is , the two isotopes are Cl-35 and Cl-37. Which isotope is more abundant?
Cl-35 is closer to , therefore it is more abundant.

38. Calculate the relative atomic mass of an element
Three things are needed to determine the relative atomic mass (aka average atomic mass)
Number of stable isotopes of the elements
Mass of each isotope
Percent abundance of each isotope

39. Calculate the relative atomic mass of an element
Steps to Calculate Relative Atomic Mass:
Convert % to decimal  move decimal 2 places to left
Multiply abundance by mass for each isotope
Add products together

40. Calculate the relative atomic mass of an element
Calculate the relative atomic mass of Chlorine. Cl-35 has a mass of and a relative abundance of 75.7%; Cl-37 has a mass of and a relative abundance of 24.3%.
75.7  .757;  .243
(.757)=26.472; (.243)= 8.983 =

41. Calculate the relative atomic mass of an element
Calculate the relative atomic mass of Oxygen. O-16 has a mass of and a relative abundance of %; O-17 has a mass of and a relative abundance of 0.037%; O-18 has a mass of and a relative abundance of 0.204%
99.76  .9976;  ; 
(.9976)=15.957; ( )= ; ( ) = =

42. Periodic Table Organization
State how the modern periodic table is organized by atomic number, groups, and periods.
Periodic Table Organization
Elements are listed in order of increasing atomic number from left to right and top to bottom
Rows are called periods
there are 7 periods 42

43. Columns are called groups or families
State how the modern periodic table is organized by atomic number, groups, and periods.
Columns are called groups or families
elements in groups have similar physical and chemcial properties 43

44. State how the modern periodic table is organized by atomic number, groups, and periods.
Classes of Elements
Metals
high conductivity, high luster (when clean), ductile, malleable
located on the left side and the center of the periodic table (excluding Hydrogen) 44

45. State how the modern periodic table is organized by atomic number, groups, and periods.
Classes of Elements
Nonmetals
nonlustrous, poor conductors, can be a gas, liquid or solid
located on the right side 45

46. State how the modern periodic table is organized by atomic number, groups, and periods.
Classes of Elements
Metalloids
properties are intermediate between metals and nonmetals
Located along stair-step line 46