Atomic Structure

Atomic Structure

• All substances are made from atoms. Each atom is made of a nucleus - containing protons and neutrons - surrounded by electrons.
• The
• atomic number is the number of protons in an atom. The elements are
• arranged in the periodic table in ascending order of atomic number.
• The
• mass number of an atom is the total of protons plus neutrons. Atoms of
• the same element with different numbers of neutrons (and hence different
• mass numbers) are called isotopes of that element.

Protons, Neutrons and Electrons

• All material things are made from atoms. There are just over one
• hundred different types of atom, called elements. Atoms can join
• together in millions of different combinations to make all the substances on Earth and beyond.
• Every atom is made of a nucleus consisting of protons and neutrons. The nucleus is surrounded by electrons.
• Protons and electrons are oppositely charged. Neutrons have no charge.
• This means the nucleus of an atom is always positively charged.
• An atom has a neutral overall charge because it has the same number of electrons as protons.
• Protons and neutrons have the same mass. Electrons have such a small mass that this can usually be taken as zero.
• 
• Pie de imagen: Structure of the atom

Relative Charges and Masses

• The atomic number (also called the proton number) is the number of protons in an atom.
• The mass number (also called the nucleon number) is the total number of protons and neutrons in an atom.
• The
• elements are arranged in the periodic table in ascending order of
• atomic number so it's easy to find the name or symbol for an atom if you
• know the atomic number.
• Different Charges
• Proton Charge - +1
• Neutron Charge - 0
• Electron Charge - -1
• Different Masses
• Proton Mass - 1
• Neutron Mass - 1
• Electron Mass - 0.0005 (almost zero) or 1/1836