The Periodic Table Trends They Might Be Giants

The Periodic Table Trends

They Might Be Giants - Meet the Elements Element Funkiness Daniel Radcliffe - Element Song

Here are some chemistry jokes with elements as punch-lines I apologize for them ahead of time

What did the silver atom say to get the gold atom’s attention? Au

There is more to the periodic table than just what can be found in the element boxes.

The periodic table is organized by increasing atomic number and elements with similar properties & same valence electrons are placed together in a column

The periodic table of elements • Is organized to maximize trends • Can be used to predict the properties of undiscovered or unfamiliar elements • Can predict reactions between elements without actually doing the experiment.

Trends we will study § § Atomic Mass Atomic Number State of Matter Metallic Character § Valence Electrons & Bonding § Electronegativity § Atomic Radius § § Ionization Energy Reactivity

Some Trends in Depth

Valence Electron Trend

What are Valence Electrons? Valence electrons are electrons in the last & highest electron energy level.

7? 3? ? 5 1? Valence shell electron pattern ? 2 4? 13?

Why are Valence Electrons Important? ?

When atoms get close to each other, the nucleus of one atom will interact with the other atom’s valence electrons. A chemical reaction and bond can result from that interaction. 9+ 9+

Valence Electrons are Importance because…. chemical reactions are just a rearranging of valence electrons & valence electrons are the cause of bonding (ionic, covalent, metallic)

Valence electrons are rearranged in chemical reactions so atoms complete their valence level of electrons.

Bonding also results from atoms completing their valence shell. When Atoms react and bond valence electrons are transferred or shared.

How the Periodic Table can be used to Predict Bonding

• Metallic – Two Metal Atoms (both atoms would like to lose valence electrons) • Covalent – Two Nonmetals (both atoms would like to gain electrons) • Ionic – Metal and Nonmetal (metal atom would like to lose electrons and nonmetal would like to gain electrons)

Ionic Bonds • A metal atom Loses electron(s) & a nonmetal Gains electron(s)

Sodium and Chlorine Video

Ionic bonds are created by attraction between oppositely charged atoms / particles.

Covalent Bonds • Sharing of electrons between two nonmetals • If two atoms need electrons to complete their valence shell they make covalent bonds. Nonmetals need electrons.

Metallic Bonds • Sharing electrons b/w two metals both of which want to lose electrons

Quiz – Valence Electrons & Bonds 1. What are valence electrons? 2. What is the pattern for increasing valence electrons? 3. Why are valence electrons important?

Quiz – Valence Electrons & Bonds Type of Bond What combo of Describe the elements make role of electrons the bond? in the bond

Bond type can more accurately be predicted with ELECTRONEGATIVITY

Electronegativity • Electronegativity is the ability of an atom to attract electrons from another atom.

Value of Electronegativity • 0 no attraction for more e • 4 great attraction for e

The absolute difference of two elements electronegativities will tell whether the bond will be covalent or ionic

Calculating Bond Character • Absolute difference b/w the electronegativities determines type of bond Metallic: Two Metals Nonpolar Covalent: 0 ≤ X ≤ 0. 4 Polar Covalent: 0. 4 < X ≤ 1. 7 Ionic: X > 1. 7

There is no firm cut-off between Ionic and Covalent it is gradual and continuous transition.

Increasing electronegativity difference + -

Fluorine Video – University of Nottingham

Atomic Radius Atomic radius (volume) is how far the outside electrons are from the nucleus. Depends on: • The strength of attraction between the electrons & nucleus (atomic number) • The number energy levels

Adding Electron Energy Levels Increases Atomic Radius • Each new energy level occupies a larger more distant region around the nucleus. 2 s 1 s 1 s

Contraction Along a Period Adding more protons without adding an energy level contracts atomic radius. The greater positive charge in the nucleus the stronger the pull the nucleus has on the electrons within the existing energy level.

Atomic Radius increases to the left (fewer p+) and down (new energy levels). The largest radius is bottom left corner (Fr).

NI 3 Demo Which is more stable NH 3 and NI 3?

IONIZATION ENERGY

Ionization energy is the energy needed to remove an electron from an atom or ion (ionization always requires energy) Energy + X (g) + X + (g) e

Ionization Energy • The stronger the nuclear charge (more protons) and smaller atoms (electrons are closer to nucleus) the I. E. is higher • IE is highest for He and lowest for Fr

st 1 Ionization Energies

Ionization Energy increases to the right and up

Reactivity Metal element reactivity increases Nonmetal element reactivity increases

Give an Explanation of Metal and Nonmetal Reactivity using Atomic Radius and Atomic Number (or Ionization Energy)

END

Good videos from University of Nottingham, Mg Video Ag Video

When atoms complete their valence energy level they lower their potential energy

Two atoms go to an ice cream shop………

Electron Affinity e + X (g)

Electron Affinity • Electron affinity measures energy lost or gained when adding an electron.

Sign of Electron Affinity Values • While IEs are all positive, some electron affinities are negative. • Negative values indicate that energy is lost by the atom when it gains an electron.

C 4. 9 Introduced: X I can state the Periodic Law and give it as the organizing principle for the periodic table.

Outermost (valence) energy level is the skin of the atom

Gain or Loss of Electrons? Positive ions are formed by metal elements. They lose electrons because that is a less energetic pathway. Nonmetals make negative ions….