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. 5.3 The periodic table is a map of the elements
Before, you learned:
The periodic table is organized into groups of elements with similar characteristics
The periodic table organizes elements according to their properties
Now, you will learn:
How elements are classified as metals, nonmetals, and metalloids
About different groups of elements
About radioactive elements
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

4. Warm-up questions
Refer to the periodic table – how are each pair of elements related?
Calcium and barium
In the same group
Lithium and carbon
In the same period
Uranium and curium
In the same period and in the actinide series
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

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

6. 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

7. 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

8. 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

9. The periodic table has distinct regions
Like a map!
Different areas indicate the properties of the elements
Three main regions:
Metals on the left (yellow)
Nonmetals on the right (except hydrogen) (green)
Metalloids in between (purple)
Reactive – how likely an element is to undergo a chemical change – combining with other materials
Atoms in Groups 1 and 17 are the most reactive
Group 18 is the least reactive
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

10. To which group do most elements belong?
Most elements are metals – look! (yellow)
Metals
elements that conduct electricity and heat well
have a shiny appearance
Can be shaped easily by pounding, bending, wire
Most are solids at room temperature (except _______)
Mercury
Na - sodium
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

11. Steel – mostly iron (some carbon)
Brass – zinc &copper
Bronze - copper & tin
Steel – mostly iron (some carbon)
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

12. Reactive Metals (Group 1)
Group 1 – the “alkali metals”
Sodium, potassium – often stored in oil to keep from air as they react rapidly with oxygen and water vapor
Ions: ____ and ____ are important in living cells
(hint: which side of the periodic table loses/gains electrons)
Group 2 – “alkaline earth metals”
Less reactive than the alkali metals, more reactive than other metals
Calcium ions – essential to bones, teeth
Magnesium – light, inexpensive metal – combined with other metals – airplane frames
Na+ K+ left side loses electrons, forming a positive ion. Group 1 loses 1 electron…hence Na+ and K+
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

13. Transition Metals Groups 3-12 Copper, gold, silver, iron
Generally less reactive than most other metals
Jewelry and coins: Gold and silver – easily shaped and not reactive – used for thousands of years
Artifacts found in museums: unchanged -they last
Coins: Dimes and quarters made of nickel – pennies made of zinc and copper
Industry:
Iron – main part of steel
Electric wires & Pipes – copper
Modern Technology – tungsten – incandescent light bulbs
Alloys – two or more metals combined
Can be stronger , less likely to corrode, or easier to shape than pure metals
Steel: iron + [nickel, chromium, manganese] (stronger than iron alone)
Brass: copper + zinc (stronger than either alone)
Jewelry: silver + copper (stronger than silver alone)
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

14. Rare Earth Elements (metals)
Top row of the two rows of metals shown outside the main body of the periodic table
“Lanthanides” (they follow lanthanum on the table)
Once believed only to be found in tiny amounts in Earth’s crust
Not as rare as originally thought – just hard to isolate in pure form
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

15. Nonmetals and metalloids
Have a wide range of properties
Nonmetals:
Many are gases at room temperature
One is a liquid (Bromine)
Solids often have a dull surface and cannot be shaped by hammering or wires
Poor conductors of heat and electric current
Ex: air – nitrogen and oxygen – both gases, different properties
Nitrogen is fairly unreactive
Oxygen readily reacts – rusting, burning
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

16. Halogens (nonmetals) Group 17 Halogens means “forming salts”
Very reactive
Often used to kill harmful microorganisms
Ex: chlorine, iodine
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

17. Noble Gases (nonmetals)
Group 18
Noble = inert gases – almost never react with other elements
Ex: colorful lights – pass an electric current through tubes of neon, krypton, xenon, argon gases glow
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

18. Metalloids Properties of both metals and nonmetals
Most common is silicon (Si)
The second most common atoms in Earth’s crust
Uses:
Semiconductors found in electronic devices
Conduct electricity under some conditions and not under others
Used in computer chips (silicon, gallium, germanium)
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

19. Some atoms can change their identity
How is identity determined?
# protons in _________
The nucleus
Chemical changes do not affect the nucleus, so chemical changes don’t change one type of atom into another
BUT…conditions may cause the number of protons to change…does this change the type of atom?
Yes!
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

20. Some atoms can change their identity
Stability of a nucleus depends on the right balance of protons and neutrons
Too few or too many neutrons, the nucleus may become unstable
Particles are then produced from the nucleus of the atom to restore balance
Results in a release of energy
May change the number of protons  different element!
Radioactivity – the process by which atoms produce energy and particles
Isotope is radioactive if the nucleus has too many or too few neutrons
Radioactive isotopes are more rare for lighter elements more common for heavier
Measured using a Geiger counter – detects particles from the break up of the atomic nucleus - clicks
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

21. Radioactivity and Medicine
Used to diagnose and treat patients
Destroy harmful tumors
Monitor activity of certain organs in body – inject a radioactive isotope and determine where and how the body is using a substance
Large does are harmful
Damage or kill cells
Energy from its particles can burn the skin
Prolonged exposure linked to cancer
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties

22. Radioactive Decay
Energy and particles are produced from the nucleus of radioactive atoms
Radioactive decay – when the number of protons, and the identity of the atom, changes
Occurs at a steady rate characteristic of the particular isotope
Half-life – the amount of time it takes for one-half of the atoms in a particular sample to decay
Ex: 1000 atoms of radioactive isotope with half-life of 1 year…how many atoms would have changed one year later? After another year?
Not affected by temperature or pressure
Can range from fractions of a second to billions of years
Simulation:
Animation:
1000, 500, 250
Atomic Structure and the Periodic Table - A substance’s atomic structure determines its physical and chemical properties