Objectives: To draw a diagram of an atom given its atomic notation. To explain and illustrate the concept of isotopes. To explain the concept of relative atomic mass. To calculate the atomic mass for an element given the mass and abundance of the naturally occurring isotopes.
Atom – the smallest unit of an element that retains its chemical properties. Atoms can be split into smaller parts.
Atoms that have the same number of protons, and hence the same atomic number, but different numbers of neutrons are called isotopes.
Particles in the Atom Each element is chemically unique. To understand why they are unique, you need to know the structure of the atom (the smallest particle of an element) and the characteristics of its components .
Particles in the Atom Electrons (-) charge no mass located outside the nucleus Protons (+) charge 1 amu located inside the nucleus Neutrons no charge 1 amu located inside the nucleus
YOU NEED TO HAVE A COPY OF YOUR PHYSICAL SCIENCE REFERENCE SHEETS READILY AVAILABLE FOR THIS WORK. ONLY USE THE NORTH CAROLINA PHYSICAL SCIENCE REFERENCE SHEETS. PRACTICE USING THIS ESSENTIAL TOOL. IT IS THE EXACT SAME SET OF REFERENCE TABLES YOU WILL USE ON YOUR EOC.
ATOMIC PARTICLES QUIZ Click on the link below and quiz yourself in a jeopardy atomic structure quiz.
Mass number versus Atomic Mass Notice mass # is just the atomic mass rounded off. Atomic mass is the mass (in a unit called amu’s) of a single atom . Mass number is the atomic mass rounded off, and equals the number of protons and neutrons together. Atomic mass 35 45 35 80 35 Br 18 22 18 40 18 Ar 20 20 20 40 20 Ca e – n 0 p + Mass # Atomic # Ca 40.08 20 Ar 39.948 18 Br 79.904 35 Atomic mass
Atoms of the same element can have different numbers of neutrons.
Different numbers of neutrons mean different masses and thus different mass numbers
These elements are called isotopes of that element.
Remember Dalton’s Atomic Theory??? One of his 4 tenants was that all atoms of the same element were alike. Ends up , DALTON WAS WRONG! Isotopes of Boron
Isotopes are like identical twins. They are almost exactly alike but not quite. For example, below are two forms of carbon. Carbon-12 Carbon-13 Carbon 13 is heavier by one neutron than Carbon-12 = proton = neutron
6 Li 7 Li Nucleus Electrons Neutrons 3 Protons 3 Electrons 3 Nucleus Electrons Neutrons 4 Protons 3 Electrons 3 3 p + 3 n 0 2e – 1e – 3 p + 4 n 0 2e – 1e – + + + Nucleus Neutron Proton Lithium-6 Nucleus Neutron Proton Lithium-7 + + +