ELEMENTS

the alchemists tried to change ordinary metals into ...........................

• iron

• silver

• gold

• stone

Seven important metals were discovered during ancient times

• gold, silver, iron, mercury, tin, copper, and lead

• gold, silver, iron, mercury, tin, copper, and aluminium

• gold, silver, iron, mercury, tin, copper, and magnesium

• gold, silver, iron, mercury, tin, copper, and sodium

What did Dmitri Mendeleev do?

• Existence of atoms

• Atomic theory

• Periodic table

• Conservation of mass

An atom consists of a central nucleus that contains protons and ..........................., with electrons orbiting around the nucleus.

• alpha particles

• quarks

• cells

• neutrons

proton number is also called

• atomic number

• mass number

• volume number

• density number

for a neutral atom proton number equals to

The Periodic Table is the arrangement of these elements by increasing ................................ ............................ and similar properties.

How can you find neutron number of an atom?

• adding proton and electron number

• subtracting proton number from electron number

• subtracting atomic mass from proton number

• adding atomic mass and proton number

Each row is called a period. Elements in a period have the same number of ............................, increasing from top to bottom.

Each ....................................... is called a group. Elements in a group have the same number of valence electrons and react in similar ways.