Organization of The Periodic Table

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Nucleus

• Center of the atom.

• Makes majority of the atom’s mass.

• Made of Protons and Neutrons.

Nucleus

Protons

• Part of the nucleus

• Have positive (+) charge

Neutrons

• Part of the nucleus

• Have neutral charge

Electrons

• Orbit around the nucleus

• Have negative (-) charge

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

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

Questions

• 1) What particles make up an atom?

• 2) What are the charges on these particles?

• 3) What particles make up the nucleus?

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?

Reading the Periodic Table

Mass

Atomic Mass

• Definition: the ~ mass of one atom of an element

• Tells us how much one atom weighs in atomic mass units.

Mass

Organization of The Periodic Table

Ordered by atomic mass. Columns arranged to form groups with similar properties

Group/Family

Period

Assessment

• Which element has the greatest atomic mass?

• Lithium

• Sodium

• Potassium

• Rubidium

Reactivity

• The ease and speed with which an element combines, or reacts, with other elements or compounds

Pure sodium reacts explosively with air

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?

Atoms have neutral charge

• # of Protons (+) = # of Electrons (-) = 0 charge

• Example: Hydrogen

• How many electrons does C have?

Electrons orbit in “shells”

• 1st shell can fit 2 electrons

• 2nd and 3rd shells can fit 8 electrons

2nd period/row

3rd period/row

1st period/row

Atoms want their shells to be full

• 2 electrons in first shell

• 8 electrons in 2nd and 3rd shells

• Examples:

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?

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?

Only use the 1st 3 periods

• 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?

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.

Metals, Metalloids, and Nonmetals

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

Reactivity of Metals

High Low

Metals will usually lose electrons when they react with other elements

Nonmetals

• Opposite of properties of metals

• Not shiny• Poor conductors• Mostly gases (at room

temperature)• Solids are brittle

Sulfur

Reactivity of Nonmetals

HighLow

Nonmetals will usually gain or share electrons when they react with other elements

Low

Some Important Nonmetals

• Carbon – important element for making up living organisms

• Noble Gases – group 18 – very nonreactive. Have full outer shells.

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

Assessment

• The atomic number is the number of

• valence electrons.

• neutrons.

• protons in the nucleus.

• electrons in the nucleus.

Assessment

• The periodic table is a chart of the elements that shows the repeating pattern of their

• energies.

• properties.

• element symbols.

• names.

Assessment

• Which piece of information cannot be found in a square on the periodic table?

• Atomic mass.

• Chemical symbol.

• Atomic number.

• Number of neutrons.

Assessment

• Which element will have properties most similar to Calcium?

• Potassium.

• Scandium.

• Magnesium.

• Bromine.

Assessment

• Which group is most likely to lose/share 2 electrons in a chemical reaction?

• 1.

• 2.

• 17.

• 18.

Assessment

• Which side of the periodic table contains most of the nonmetals?

• Left side.

• Right side.

• Middle.

Assessment

• Which is not a property of nonmetals?

• Brittle.

• Nonmalleable.

• High conductivity.

• Most are gases at room temperature

Assessment

• Which metal is probably the most reactive?

• Potassium

• Calcium

• Scandium

• Titanium

Assessment

• Which nonmetal is probably the most reactive?

• Nitrogen

• Oxygen

• Fluorine

• Neon