Basic Facts

• Define Matter?

  Matter is a physical substance that has mass.
• What is an atom?

  Atoms are individual units of matter that make up all matter.
• What makes up an atom?

  A densely packed nucleus of protons and neutrons surrounded by electrons
• What are the properties of a proton?

  Proton has a charge of +1 and a relative mass of 1
• What are the properties of a neutron?

  Neutron has a charge of nothing and a relative mass of 1
• What are the properties of an electron?

  Electron has a charge of -1 and no relative mass
• Why do electrons remain near nucleus?

  Due to electrostatic forces of attraction.
• What letter represents the mass number?

  A
• What letter represents the atomic number?

  Z
• What letter represents the Chemical symbol?

  X
• Is mass above atomic number in nuclear symbol?

  Yes.
• What is an isotope?

  An atom with a different mass, different number of neutrons.
• What is an ion?

  An atom with a different number of electrons.
• Define Valency?

  the number of electrons in the outer shell, increasing across a period due to the increase in atomic number but constant down a group.
• Define Molecule.

  Contains the same type of atoms, existing as individual atoms or atoms held together by chemical bonds.
• Define Molecule.

  Two or more atoms of the same element joined together chemically.
• Define Compound.

  Two or more atoms of different elements joined chemically.
• What is a mixture?

  is made up of two or more substances that are not chemically bonded. The properties of a mixture depend on the identity and amount of each substances that is a component of the mixture.