1)Explain how atoms of the element helium (He) are formed in a star. ( 2 marks)

2) Explain how atoms of very heavy elements, such as gold (Au), were formed. (2 marks)

1)Explain how atoms of the element helium (He) are formed in a star. ( 2 marks)

fusion (1)of hydrogen/H (atoms)(1)

2) Explain how atoms of very heavy elements, such as gold (Au), were formed. (2 marks)

•fusion of other /lighter atoms/elements (1)

•during super nova/explosion ofstar(s) (1)

The Modern Periodic table

L.O.:

Explain how the elements fit into groups in the periodic table.

Assess the importance of the periodic table.

The History ofthe Modern

Periodic Table

During the nineteenth century, chemists began to put the

elements into groups according to similarities in their physical

and chemical properties. The end result of these studies was our modern periodic table.

John NewlandsJohn Newlands

1838 - 18981838 - 1898

Law of Octaves

In 1863, he suggested that elements be arranged in “octaves” because he noticed (after arranging the elements in order of increasing atomic mass)

that certain properties repeated every 8th element.

John NewlandsJohn Newlands

Newland looked at the elements and found a repeating pattern. His table had __ groups instead

of the __ we have today.

1 2 3 4 5 6 7

78

Dmitri MendeleevDmitri Mendeleev

1834 - 1907

In 1869 he published a table of the elements organized by

increasing atomic mass.

These are the elements known at this time

• Mendeleev left vacant spaces where unknown elements should fit.

• stated that if the atomic weight of an element caused it to be placed in the wrong group, then the weight must be wrong!

• He even corrected the atomic masses of Be, In, and U

Mendeleev...

• was so confident in his table that he was so confident in his table that he used it to predict the physical used it to predict the physical properties of three elements that properties of three elements that were yet unknownwere yet unknown!

Mendeleev...

SMARTY PANTS!!

After the discovery of these unknown elements between 1874 and 1885, and the fact that Mendeleev’s predictions for Sc, Ga, and Ge were amazingly close to the actual values, his table was generally accepted.

However, in spite of Mendeleev’s great achievement, problems arose when new elements were discovered and more accurate atomic weights determined. By looking at our modern periodic table, can you identify what problems might have caused chemists a headache?

Ar and KCo and NiTe and I

Th and Pa

Glenn T. SeaborgHe is the only person to have an

element named after him while still alive.

1912 - 1999

"This is the greatest honor ever bestowed upon me - even better, I

think, thanwinning the Nobel Prize."

Periodic Table Geography

The horizontal rows of the periodic table are called PERIODS.

The vertical columns of the periodic table are called GROUPS, or FAMILIES.

The elements in any group of the periodic table have similar physical and

chemical properties!

Periodic LawPeriodic Law

When elements are arranged in order of increasing atomic number,

there is a periodic pattern in their physical and chemical properties.

Alkali Metals

Alkaline Earth Metals

Transition Metals

Halogens

Workbook page 104-106

In groups of 3 or 4: task C3.1