7.1 The periodic table Flashcards
How did Mendeleev arrange the elements
In order of atomic mass (nothing was known about subatomic particles and atomic number at the time).
In groups with similar properties, if they didn’t fit, he swapped elements around and left gaps to compensate for undiscovered elements
He also predicted properties of the missing elements from trends
What did Mendeleev predict in 1871
The properties of an undiscovered element called ‘ekasilicon’
It was later discovered in 1886 and was named germanium
His predictions were not far off
The periodic table in 2014
114 elements
Arranged in 7 horizontal periods
Arranged in 18 vertical groups
What does the arrangement show
The pattern and shape show the trends among the elements
Linked to their physical and chemical properties
What can the table be used for
Predicting the properties of elements and their compounds
How are the elements arranged
From left to right, there is an increase in atomic number
One extra proton
What are groups
The vertical columns in the periodic table
What do elements in the same group have in common
Atoms with the same number of outer-shell electrons and similar properties
What are periods
The horizontal rows in the periodic table
What does the period show
The number of the period gives the number of the highest energy electron shell in an elements atoms
What is periodicity
The repeating trend in properties of the elements across each period
What is each element determined by
Its electron configuration, particularly the highest energy electron shell
Each period starts with an ______ in a new highest ______ ______
Electron
Energy shell
What are blocks
The elements can be divided into blocks corresponding to their highest energy sub-shell
s, p, d and f blocks
Old group numbers
1, 2, 5, 6, 7, 0
