The Structure of an Atom Chapter 4.2

Warm-up: KWL Chart - ATOMS What I Know About Atoms What I Would Like to Learn About Atoms What I Have Learned About Atoms

Properties of Subatomic Particles There are 3 types of subatomic particles in an atom There are 3 types of subatomic particles in an atom –Protons –Electrons –Neutrons

Protons POSITIVELY charged particle located in the nucleus of an atom POSITIVELY charged particle located in the nucleus of an atom Each element contains at least 1 proton Each element contains at least 1 proton Each proton has a charge of +1 Each proton has a charge of +1 Rutherford discovered that the amount of positive charge varies among elements Rutherford discovered that the amount of positive charge varies among elements

Electrons NEGATIVELY charged subatomic particle that is found in the space outside the nucleus NEGATIVELY charged subatomic particle that is found in the space outside the nucleus Each electron has a charge of 1- Each electron has a charge of 1- Its mass is so small that it is not taken into consideration Its mass is so small that it is not taken into consideration

Neutrons Neutral subatomic particle that is found in the nucleus of an atom. Neutral subatomic particle that is found in the nucleus of an atom. Its mass is almost exactly equal to that of a proton Its mass is almost exactly equal to that of a proton

Comparing Subatomic Particles Protons, Neutrons, and Electrons can be distinguished by mass, charge, and location in the atom Protons, Neutrons, and Electrons can be distinguished by mass, charge, and location in the atom ParticleSymbol Relative Charge Relative Mass Actual Mass Electrone-1-1/ x10-28 Protonp x10-24 NeutronnO11.675x10-24

Fun Facts About Atoms

Atomic Number Atomic number of an element is equal to the number of protons in the nucleus of that element Atomic number of an element is equal to the number of protons in the nucleus of that element –Atomic number = # protons Atoms of different elements have different numbers of protons Atoms of different elements have different numbers of protons

Electrically Balanced Atoms The number of protons in an atom is balanced by the number of electrons in the atom so that the atom does not carry a net charge The number of protons in an atom is balanced by the number of electrons in the atom so that the atom does not carry a net charge So, the atomic number also tells us the # of electrons So, the atomic number also tells us the # of electrons

Mass Number Mass number = # protons + # neutrons (in the nucleus of an atom) Mass number = # protons + # neutrons (in the nucleus of an atom)

Calculating the Number of Neutrons Number of Neutrons = Number of Neutrons = Mass number – Atomic Number

Isotopes Isotopes are atoms of the same element that have different numbers of neutrons Isotopes are atoms of the same element that have different numbers of neutrons Isotopes of an element have the same atomic number, but different mass numbers because they have different numbers of neutrons Isotopes of an element have the same atomic number, but different mass numbers because they have different numbers of neutrons

More About Isotopes..

Carbon Isotopes