“Meet the Elements” by They Might Be Giants

What is an element vs. a compound?

Some elements can be found “native” in nature. People have known about these for a long time!

Then people wanted to turn worthless base metals into gold…

“More than 300 years ago, in 1669, Hennig Brand, a Hamburg alchemist, like most chemists of his day, was trying to make gold. He let urine stand for days in a tub until it putrified. Then he boiled it down to a paste, heated this paste to a high temperature, and drew the vapours into water where they could condense - to gold.

To his surprise and disappointment, however, he obtained instead a white, waxy substance that glowed in the dark.Brand had discovered phosphorus, the first element isolated other than the metals and non-metals, such as gold, lead and sulphur, that were known to the ancient civilisations.”

Periodic Table of Elements may SEEM boring…But people LOVE to organize things:

In 1869, Mendeleev organized the elements by their properties.

He noticed a repeating pattern in the ~60 elements known at the time when he organized them by atomic mass!

Father of the Periodic TableDmitri Mendeleev (1834-1907)

Video – Alkali Metals

Gallium

Germanium

Two Years Later…

Father of the Modern Periodic Table:Henry Moseley (1887-1915)

in 1913, through his work with x-rays, Moseley discovers the actual nuclear charge of the elements, which we now call atomic numbers. Moseley then rearranges the periodic table by increasing atomic number. This is the periodic table we use today- the modern periodic table.

Father of the Modern Periodic Table:Henry Moseley (1887-1915)

*“There is in the atom a fundamental quantity which increases by regular steps as we pass from each element to the next. This quantity can only be the charge on the central positive nucleus.”

-Henry Moseley

Label your periodic table:\

Which has similar properties?

\

Why do elements in the same group have similar chemical properties?

Label these sections:

Ductile, malleable, good conductors

Brittle, poor conductors

Group 1: Alkali Metals

• Soft – cut with a knife!

• Highly reactive!• - 1 valence electron

– Explodes in water!– “Rusts” almost instantly– Never found in elemental

form in nature• You have to store them

coated in mineral oil or argon to keep them from reacting!

Group 2: Alkaline Earth MetalsStill reactive, but not as reactive as the alkali

metals.

2 valence electrons

Group 3-12: The Transition Metals• Generally stable and malleable metals.

• Contains the only magnetic elements – Fe, Co, Ni

• Contains gold, silver, and platinum

• Have various numbers of valence electrons

 

Group 17: The Halogens• Highly reactive non-metals• 7 valence electrons

• Form diatomic molecules (like Cl2) that are more stable than elemental form

• Fluorine is so reactive that it will attack glass and can even force the noble gases to form compounds with it– Fluorine is a jerk…but is not the same as fluoride!

Group 18: The Noble GasesNoble gases – gaseous elements with

EXTREMELY low reactivities (they are inert)8 valence electrons