History
Who created the periodic table in 1869?
Dmitri Mendeleev
What number tells how many protons an atom has?
Atomic Number
What are the vertical columns called?
Groups
Where are metals located on the periodic table?
Left side and center
What group are the alkali metals?
1
Mendeleev originally arranged elements by increasing what?
Atomic mass
What are the four main pieces of information on an element key?
Atomic number, symbol, name, atomic mass
What are the horizontal rows called?
Periods
Which type of element is usually brittle and a poor conductor?
Nonmetals
What group are the noble gases?
18
What scientist discovered the importance of atomic number?
Henry Moseley
What is the symbol for hydrogen?
H
How many groups are on the periodic table?
18
What type of element has properties of both metals and nonmetals?
Metalloids
What family is extremely unreactive?
Noble Gasses
Why did Mendeleev leave gaps in his periodic table?
He predicted undiscovered elements.
What does atomic mass represent?
The average mass of an atom’s particles
Elements in the same group have similar what?
Properties
Name TWO properties of metals.
What family forms salts when combined with metals?
Halogens
How is today’s periodic table organized differently from Mendeleev’s original table?
By atomic number instead of atomic mass.
Why is the periodic table important to scientists?
It organizes elements and helps predict properties.
Elements in the same period have the same number of what?
Electron shells
Why are metalloids useful in technology?
They can conduct electricity better than nonmetals but not as well as metals.
Why are alkali metals stored in oil?
They react quickly with water and air.