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Who publised the first table of chemcical elements?
Mendeleev
Why did Mendeleen leave gaps in the table?
He assumed other elements were yet to be discocvered
in 1817, what did Dobëreiner classify the elemets based on?
Their atomic mass
Why did Mendeleen call it the "Periodic table of elements"?
Becase the properties of the elements were repeated at a certain frequnecy.
What did John A.R. Newland organize the elemets accrding to?
Their mass
What is the outermost layer occupied by electrons called?
The valence layer
In the current periodic table, the chemical elemets are organized in ascending order according to what?
Their atomic number
How many rows are there in the periodic table? (don't look!) What are the rows called?
There are 7 rows and they are called periods
What do the elements in a row have in common?
They have the same number of of layers of electrons
How many columns are there? What are the columns called?
There are 18 colums and they are called groups.
What do all the elements in a column (group) have in common?
They all have the same number of electrons in their outer layer
What are the elemets in group 1 called? How many electrons do they have in the outer layer?
Alkali metals. They have 1 electron in the outer layer.
What are the elements in group 17 called? How many electrons do they have in the outer layer?
Haolgens. They have 7 electrons in the outer layer.
Which group of elements do not form ions?
Noble gases (group 18)
What do elements that are classified as metals tend to do in regards to electrons and ions? (gain, lose...)
Metals tend to lose electrons and form positive ions
How did Henry Moseley organize elements on the period table? (The same way that they are organized now)
Based on their number of protons
