Good Morning!

To begin today, you will need:1. 3 different colors of writing utensils

o colored pencils are up front for your use

2. One blank periodic tableo Up front

3. One packet of notes (green)o Up front

The Periodic Table &

Periodic Trends

Groups/FamiliesRepresentative Elements

Groups 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A

*CAS vs. IUPAC (old) naming systems

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Periods

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Slide 7 of 31

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Periodic Trends > Trends in Atomic Size

The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined.

6.3

Trends in Atomic Size

• Moving left to right, e- are added to the same energy level, while protons are added to the nucleus

• The e- are attracted more strongly and are pulled in closer to the nucleus, making the atomic size smaller.

Ions• When an atom loses or gains electrons it becomes

an ion.• A positively (+) charged ion is called a cation (+).

– Lost electrons, so has more protons than electrons– Metals want to lose their valence electrons; therefore

only metals can be cations.• A negatively (-) charged ion is called an anion (-).

– Gained electrons, so has more electrons than protons– Non-metals want to gain valence electrons; therefore

only non-metals can be anions.

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Ions• When atoms gain or lose electrons, they want to

get to have a “full” outer energy shell.• The octet rule states that elements gain or lose

electrons to attain an electron configuration of the nearest noble gas.

• Metals lose electrons to go down to the previous energy shell, either full at 2 electrons (Li), or 8 electrons.

• Non-metals gain electrons to fill their outermost shell to 8 electrons.

Which is bigger…. the cation or the

original atom?

Which is bigger…. the anion or the original atom?

Trends in Ion Size

Students label trend on notes

Trends in 1st Ionization EnergyEnergy generally increases

Energy generally increases

Ionization Energy:The energy required to remove an electron from an atom.

Ionization Energies

Trends in Electronegativity

ElectronegativityThe ability of an atom of an element to attract electrons when the atom is in a compound.

Things to Remember• Atomic Radius

– ½ the distance between the nuclei of two atoms of the same element when the atoms are joined

• Ions– Cation is a positively (+) charged ion (more protons than

electrons)– Anion is a negatively charged ion (more electrons than protons)

• Ionic size– Cations are always smaller than the atoms from which they form– Anions are always larger than the atoms from which they form

• The trends that exist among these properties can be explained by variations in atomic structure.