The periodic table Flashcards
Before protons, neutrons and electrons were discovered, how did scientists classify elements?
According to their atomic weights
Describe Mendeleev’s periodic table.
- arranged elements based on increasing atomic weight
- had gaps in it (for elements not yet discovered)
- elements with similar properties lined up in groups
Whose periodic table does this show?
Mendeleev
What is a period?
A horizontal row in a periodic table
What is a group?
A vertical column in a periodic table
How are elements with similar properties arranged in the modern periodic table?
Into groups (vertical columns)
How many electrons fit in the first shell of an atom (nearest the nucleus)?
Two
How many electrons can fit in the second and third shell of an atom?
Eight
What is the atomic number of this atom?
11
What is the electron configuration of this atom?
2,8,1
What does the period number tell you about an atom?
The number of shells it has
What is the period number of this atom?
3
What does the group number tell you about an atom?
The number of electrons it has in its outer shell
In which group would this atom be found in the periodic table?
Group 1
How do metals form ions?
By losing electrons (to form positive ions)
Describe how a sodium ion is formed.
Sodium atoms lose one electron to form a sodium ion with a charge of +1.
