How do you find the period of an element from its electron arrangement?

Count the number of occupied shells

Why do elements in the same group have similar chemical properties?

They have the same number of outer-shell electrons

To keep elements with similar properties together and allow for undiscovered elements

The solution turns orange or brown as bromine is displaced

They have full outer electron shells

16questions. Pick an answer and you'll see why right away.

What is a compound?
Which technique separates a soluble solid from its solution as crystals?
On a chromatogram, the solvent front moves 10 cm and a spot moves 4 cm. What is the Rf value?
What is the relative charge on a neutron?
An atom has a mass number of 39 and an atomic number of 19. How many neutrons does it have?
What are isotopes?
Boron has isotopes boron-10 (20 percent) and boron-11 (80 percent). What is its relative atomic mass?
What is the electron arrangement of an atom with atomic number 11?
How do you find the period of an element from its electron arrangement?
Why do elements in the same group have similar chemical properties?
How is the modern Periodic Table ordered?
Why did Mendeleev leave gaps in his Periodic Table?
What is the trend in reactivity down Group 1?
What is observed when chlorine is added to potassium bromide solution?
Why are the noble gases unreactive?
Which separation method is used to obtain pure water from sea water?