The Periodic TableCHAPTER 10---LESSON # 1Periodic: repeating, according to a pattern. Ex: days of the week, months, years, etc.Dmitri Mendeleev- “Father of the Periodic Table. Late 1800’s. Arranged PT by the physical and chemical properties of the elements.

• Mendeleev arranged the elements in order of increasing atomic mass.

• The PT is a chart of the elements arranged into rows and columns according to their physical and chemical properties.

Early 1900’s – Henry Moseley

• Henry Moseley changed the PT to be arranged in order ofIncreasing Atomic # instead of increasing atomic mass.

• By doing this, the groups/families then had similar physical And chemical properties ( columns )

Bergmann video on size of atom

https://www.ted.com/talks/just_how_small_is_an_atom#

How is the PT arranged NOW?• By increasing atomic number.• By their state--solid, liquid or gas at room temperature.• By groups – due to their physical and chemical properties.• By 3 main groups: metals, metalloids and non-metals

Groups and Periods• Groups or Families: 18 of them. They go down ( Vertical ) on the table.

• Periods: 7 of them. They go across (horizontal ) on the table.

Like a calendar

3 main categories of the PT

1. Metals, Non-metals and Metalloids

• Most of the table, ¾ , are metals.

• Metals are on the left side of the “staircase,” except for H on the far left. ( NOT A METAL!)

• Nonmetals, plus H, are to the right of the “staircase.” Many of these are gases.

• Metalloids are ON the staircase.

The Periodic Law

It states that the chemical and physical properties of elements are periodic or repeating functions of their atomic numbers.