The Periodic TableThe Periodic Table

Dmitri MendeleevDmitri Mendeleev

Created a table arranged by increasing atomic mass and chemical characteristics

Wrote the periodic law - Chemical physical properties of the elements are a periodic function of their atomic mass.

Predicted the characteristic of three undiscovered elements, Germanium, Gallium and Scandium

11 2 2 3 3 4 4 5 5 7 7 8 8 99 10 10 1111 1313 1414 1515 1616 1717 1919 2020 2121 2222 2323 2424 25 25 26 26 2727 2828 2929 3030 3131 3232

Mendeleev sorted the elements by similar properties, and then by increasing atomic mass.

So elements 1 , 9, 17, 25, all had similar properties. Each column or family had Its own set of characteristics.

He saw that there should be an element with the weight of 12 and it should alsoHave the characteristics of elements 4, 20, and 28.

Problems Problems

Not all the element fell into place as they Not all the element fell into place as they should, but it was the best table at the time. should, but it was the best table at the time.

Henry MoseleyHenry Moseley

Found a way to count protonsFound a way to count protons Then the table was then rearranged Then the table was then rearranged

according to increasing atomic number.according to increasing atomic number. ( # of protons) ( # of protons) This removed the problems in Mendeleev’s This removed the problems in Mendeleev’s

table.table.

How is the table arranged?How is the table arranged?

What are?What are?

Metals Metals Nonmetals Nonmetals Metalloids Metalloids Active metalsActive metals noble gasesnoble gasesTransition metals Transition metals Halogens Halogens Alkali and alkaline earth metalsAlkali and alkaline earth metals

Atomic radius and how it variesAtomic radius and how it varies

General patternGeneral pattern

Ionization and atomic sizeIonization and atomic size

X + energy X + energy → X→ X++ + e + e- -

An ion is a charged particle ( positive or An ion is a charged particle ( positive or negative) negative)

Anion = negative cation = positiveAnion = negative cation = positive The energy required to make a + ion is The energy required to make a + ion is

called ionization energy.called ionization energy.

The smaller the atomic radius the harder it is The smaller the atomic radius the harder it is to remove an electron. ( explain)to remove an electron. ( explain)

Electrons (-) closer to the nucleus(+) are Electrons (-) closer to the nucleus(+) are held more strongly.held more strongly.

Pattern on the table, as you move down a Pattern on the table, as you move down a family ionization energy gets lower.family ionization energy gets lower.

As you move left to right ionization energy As you move left to right ionization energy gets higher.gets higher.

Ionization energyIonization energy

Successive ionization energy Successive ionization energy

It is all ways harder to remove the second It is all ways harder to remove the second and third electron , do to the fact the same and third electron , do to the fact the same number of protons is now holding fewer and number of protons is now holding fewer and fewer electrons. fewer electrons.

And some times messing with a more stable And some times messing with a more stable electron configuration.electron configuration.

Atomic radius verse ionic radiusAtomic radius verse ionic radius

+ ions are smaller than their parent atom+ ions are smaller than their parent atom - ions are larger than their parent atom. - ions are larger than their parent atom.

Why? Its related to the number of protons Why? Its related to the number of protons and electrons present.and electrons present.

Atomic and ionic radiiAtomic and ionic radii

ElectronegativityElectronegativity

The measure of an atoms attraction for a The measure of an atoms attraction for a shared electron. shared electron.

Similar to ionization energy, it is still a Similar to ionization energy, it is still a measure of an atoms attraction for measure of an atoms attraction for electrons. electrons.

Pattern on the table is the same.Pattern on the table is the same.

Electron affinityElectron affinity

The energy released when an atom gains The energy released when an atom gains an electron.an electron.

X + eX + e-- → X→ X-- + energy + energy Opposite of ionization energy Opposite of ionization energy