The Periodic Table- Development of Periodic Table Flashcards
Before the discovery of protons, electrons and neutrons, scientists ordered the elements by their ______ ______.
Before the discovery of protons, electrons and neutrons, scientists ordered the elements by their atomic weight.
__________ placed elements in more appropriate places, grouping elements with similar __________ so patterns could be seen. This meant he sometimes left gaps or changed the order of ______ ______.
Mendeleev placed elements in more appropriate places, grouping elements with similar properties so patterns could be seen. This meant he sometimes left gaps or changed the order of atomic weight.
Elements with properties Mendeleev predicted were ___________ and filled the gaps.
Elements with properties Mendeleev predicted were discovered and filled the gaps.
The elements on the modern _________ _____ are arranged in order of ___________ atomic number.
The elements on the modern periodic table are arranged in order of increasing atomic number.
Elements are arranged in columns called ______ (going down) on the periodic table.
Elements are arranged in columns called groups (going down) on the periodic table.
The number of electrons in the _________ _____ of an atom is the same as its _____ on
the periodic table.
The number of electrons in the outermost shell of an atom is the same as its group on
the periodic table.
what does the word periodic mean
occurring at regular intervals
true or false?
elements with similar properties are in periods
true
why do elements in the same group react in the same way
because they have the same number of electrons in their outer shell
how did John newland arrange the elements
order of increasing atomic weight and noticed that every 8th element reacts in the same way
what is newlands law called
law of octaves
what problems did newlands system
by using increasing atomic weight, some elements ended up being grouped with other elements that had completely different properties
what did Mendeleev develop
the first modern periodic table
how did Mendeleev arrange the elements
in increasing atomic weight
what two things did Mendeleev do that no one else had
- if he needed to he would switch the order of specific elements so they fitted the patterns of the other elements in the group
- he left gaps in the periodic table for elements that hadn’t been discovered yet
