1. Unit 2/B: Chemical Interactions
Chapter 5: Atomic Structure and the Periodic Table
Chapter 6: Chemical Bonds and Compounds
Chapter 7: Chemical Reactions
Chapter 8: Solutions
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

2. Chapter 5: Atomic Structure and the Periodic Table
A substance’s atomic structure determines its physical and chemical properties
5.1 Atoms are the smallest form of elements
5.2 Elements make up the periodic table
5.3 The periodic table is a map of the elements
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

3. 5.2 Elements make up the periodic table
Before, you learned:
Atoms have a structure
Every element is made from a different type of atom
Now, you will learn:
How the periodic table is organized
How properties of elements are shown by the periodic table
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

4. Warm-up questions
The atomic number of an atom is the number of protons and neutrons in the nucleus
Atomic mass number
Isotopes are atoms of the same element, but with a different number of neutrons
True
When an atom gives up an electron, it becomes an ion with a negative charge
positive
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

5. Table 1. Characteristics of Some Elements
1. Complete the table below, considering 'normal' atoms only (not ions or isotopes).
Table 1. Characteristics of Some Elements
What is the atomic weight of the normal oxygen atom? Of the normal argon atom?
3. What is the atomic weight of a hydrogen atom? Of a hydrogen ion?
Element
# Electrons
# Protons
# Neutrons
hydrogen 1
helium 2
sodium 11
chlorine 17
argon 18
carbon 6
nitrogen 7
oxygen 8
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

6. Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

7. Atomic Numbers and Mass Numbers
All atoms are composed of the same particles…
Different numbers of protons in the nucleus
Atomic number = # protons in the nucleus
Atomic mass number = # protons + # neutrons
Same elements have same # protons but not always the same # neutrons, so may have different atomic masses
Ex: Chlorine atoms have 17 protons, some have 18 neutrons, some have 20 neutrons = Chlorine isotopes
Isotopes: atoms of the same element that have a different number of neutrons
Chlorine-35, Chlorine-37
# protons? # neutrons?
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

8. Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

9. Formation of Positive Ions
If the atoms loses one electron, the charges are no longer balanced: one more proton than electrons
Size is different: fewer electrons, less repulsion
Lose one electron: X+, lose two electrons: X2+ Ex: Na+, Ca2+
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

10. Formation of Negative Ions
If the atoms gain one electron, the charges are no longer balanced: one less proton than electrons
Size is different: more electrons, more repulsion
Gain one electron: X-, gain two electrons: X2- Ex: Cl-, O2-
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

11. 5.2 Elements make up the periodic table
Elements can be organized by similarities
Masses
Can find the mass of a very large number of atoms of a certain elements and infer the mass of a single one of them
Can vary for an element: isotopes
“atomic mass” is actually the average mass of all the element’s isotopes
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

12. Mendeleev’s Periodic Table
Russian chemist, Dmitri Mendeleev
1860’s – how to organize the elements based on physical and chemical properties?
He made cards that contained atomic mass and properties
He looked for a relationship between the properties and atomic mass
He created a chart:
Rows: elements showing similar chemical properties
Atomic mass increased by moving down each vertical column
1869 – first periodic table – “periodic” – shows a periodic, or repeating, pattern of properties of the elements
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

13. Predicting New Elements
Mendeleev left empty spaces on the table where no known elements fit the pattern
Predicted new elements fitting the spaces would eventually be discovered – described their properties!
Six years later the “?” after aluminum (Al) was discovered: “gallium
In the next 20 years, two others were discovered
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

14. The periodic table organizes the atoms of the elements by properties and atomic number
New table: elements with similar properties are now found in columns, not rows…and atoms are now arranged by atomic number, not mass
How to read the periodic table?
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

15. Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

16. How to Read the Periodic Table?
The number at the top is the atomic number = # protons in the nucleus
Chemical symbol - one or two letters; temporary symbols for not-yet named elements have three-letter symbols
Name of element
number at bottom is the “average atomic mass” of all the isotopes of the elements
Color of symbol is the state of matter at room temperature
Color of background color of box indicates whether metal, nonmetal, or metalloid (5.3)
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

17. Groups and Periods
Elements in a vertical column show similarities in their chemical and physical properties
Known as a group
Labeled by a number at the top of the column
Sometimes a group is called a family of elements because they seem to be related
Ex: Group 17 – “Halogen” group
Tend to combine easily with other elements and compounds, especially elements in Gropus 1 and 2
Different physical properties
At room temperatures: Flourine and chlorine are gases, bromine is a liquid, iodine and astatine are solids
Ex: Group 1 –
Some metals – lithium, sodium, potassium, for example – react violently with water
Horizontal row in the periodic table = period
Properties of elements change in a predictable way from one end of a period to the other
Ex: Period 3 = elements on far left are metals, far right are nonmetals
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

18. Trends in the Periodic Table
An element’s position in the table can give information about that element
Ions form by an atom gaining or losing electrons
Atoms of elements on the left side of the table form positive ions
Group 1 atoms lose an electron to form ions 1+
Group 2 atoms lose two electrons to form ions 2+
Group 18 atoms normally do not form ions
Group 17 often form ions 1-
Group 16 often form ions 2-
Groups 3 through 12 all form positive ions with varying charges
Sizes of atoms vary across periods and within groups
Size affects how the atom will react with another atom
Densities follow a pattern
Generally increases from top of a group to the bottom
Within a period, elements at the left and right sides are the least dense, the middle are the most dense
Ex: Osmium (Os) has the highest known density
Trends are a valuable tool, though exact size or density of an atom cannot be predicted exactly
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

19. Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

20. Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

21. Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties