The periodic table organizes the elements based on their atomic structure, especially the number of protons and electrons. Elements in the same column usually have similar properties because they have the same number of valence electrons. The periodic table can be used to predict an element's identity, properties, and reactivity based on its location on the table.
6. Atomic Number
• Definition: the number of protons in the
nucleus
• Tells us the identity of the element.
Every element is defined by the number of protons in its nucleus
7. Isotopes
• Atoms with the same number of protons
but different numbers on neutrons
• Example: Carbon
So you can change the number of neutrons and the element still maintains its identity
8. Questions
• 1) What particles make up an atom?
• 2) What are the charges on these
particles?
• 3) What particles make up the nucleus?
9. Questions
• 1) What is Oxygen’s atomic number?
• 2) How many protons does Oxygen have?
• 3) If I have 4 protons what element am I?
• 4) If I have 4 neutrons what element am I?
14. Reactivity
• The ease and speed
with which an element
combines, or reacts,
with other elements or
compounds
Pure sodium reacts explosively
with air
15. Groups/families of elements have similar reactivity
Group 1: metals that react violently with water
Group 18: Gases that barely react at all
Why do groups/families of elements react the same way?
16. Atoms have neutral charge
• # of Protons (+) = # of Electrons (-) = 0 charge
• Example: Hydrogen
• How many electrons does C have?
17. Electrons orbit in “shells”
• 1st shell can fit 2 electrons
1st period/row
• 2nd and 3rd shells can fit 8 electrons
2nd period/row
3rd period/row
18. Atoms want their shells to be full
• 2 electrons in first shell
• 8 electrons in 2nd and 3rd shells
• Examples:
19. Question
• How many electrons does an oxygen
have?
• How many electrons are in its outer shell?
• Which group is oxygen most likely to react
with?
20. Question
For the first 3 periods:
1) How many electrons are in the outer shell of each element in group 1? Group 2?
Group 13? Group 14? Group 15? Group 16? Group 17? Group 18?
2) How many electrons does each element in each group above need to fill its
outer shell?
3) Which groups are the most likely to react with one another?
4) Which group is least likely to react with any other group?
21. Only use the 1 3 periods st
• For the first 3 periods:
• 1) How many electrons are in the outer shell of each
element in group 1? Group 2?
• Group 13? Group 14? Group 15? Group 16? Group 17?
Group 18?
• 2) How many electrons does each element in each
group above need to fill its
• outer shell?
• 3) Which groups are the most likely to react with one
another?
• 4) Which group is least likely to react with any other
group?
22. Take home message
• The properties of an element can be
predicted from its location on the Periodic
Table
• This is largely a result of the number of
electrons in their outer shell.
24. Metals
• Shiny
• Solids (at room temp)
• Malleable – can be
hammered flat
• Ductile – can be pulled
into wire
• High Conductivity –
ability to transfer heat or
electricity to another
object
25. Reactivity of Metals
High Low
Metals will usually lose electrons when they react with other elements
26. Nonmetals
• Opposite of properties
of metals
• Not shiny
• Poor conductors
• Mostly gases (at room
temperature)
• Solids are brittle
Sulfur
27. Reactivity of Nonmetals
Low
Low High
Nonmetals will usually gain or share electrons when they react with other elements
28. Some Important Nonmetals
• Carbon – important element for making
up living organisms
• Noble Gases – group 18 – very
nonreactive. Have full outer shells.
29. Metalloids
• Inbetween metals and
nonmetals
• Solids (at room temp)
• brittle and hard
• Semiconductors – can
conduct electricity under
some conditions but not
others.
– very important for
computer chips
• Most common example –
Silicon – in sand and
glass
30. Assessment
• The atomic number is the number of
• valence electrons.
• neutrons.
• protons in the nucleus.
• electrons in the nucleus.
31. Assessment
• The periodic table is a chart of the
elements that shows the repeating pattern
of their
• energies.
• properties.
• element symbols.
• names.
32. Assessment
• Which piece of information cannot be
found in a square on the periodic table?
• Atomic mass.
• Chemical symbol.
• Atomic number.
• Number of neutrons.
33. Assessment
• Which element will have properties most
similar to Calcium?
• Potassium.
• Scandium.
• Magnesium.
• Bromine.
34. Assessment
• Which group is most likely to lose/share 2
electrons in a chemical reaction?
• 1.
• 2.
• 17.
• 18.
35. Assessment
• Which side of the periodic table contains
most of the nonmetals?
• Left side.
• Right side.
• Middle.
36. Assessment
• Which is not a property of nonmetals?
• Brittle.
• Nonmalleable.
• High conductivity.
• Most are gases at room temperature
37. Assessment
• Which metal is probably the most
reactive?
• Potassium
• Calcium
• Scandium
• Titanium
