The Chemistry of Life, The Nature of Matter The Nature of Matter Hierarchy of Science A hierarchy is a system of organizing and ranking things. 2-1 The Nature of Matter A hierarchy is a system of organizing and ranking things. It comes from the Greek, meaning sacred rule Hierarchy of Science 2-1 The Nature of Matter Math provides tools for measuring basic quantities. Mathematics 2-1 The Nature of Matter Math provides tools for measuring basic quantities. Physics studies basic things, like matter, motion and energy. Mathematics PHYSICS 2-1 The Nature of Matter Math provides tools for measuring basic quantities. Physics studies basic things, like matter, motion and energy. Chemistry studies the ways that matter and energy are arranged. Mathematics PHYSICS CHEMISTRY 2-1 The Nature of Matter BIOLOGY studies a particular kind of arrangement of matter and energy: LIFE ! Mathematics BIOLOGY PHYSICS CHEMISTRY other stuff 2-1 The Nature of Matter Atoms: appear as elements in the Periodic Table have a dense nucleus at their center consist mostly ofempty space ! 2-1 The Nature of Matter Subatomic Particles Particle Symbol A.M.U.* Charge Location proton positive proton p + 1 positive nucleus neutron neutral neutron n 1 neutral nucleus electron * negative electron e - 0* negative cloud Actually, an electron has a mass, but its very small: 1,867 times smaller than the proton or the neutron 2-1 The Nature of Matter nucleus of an atom of carbon: The Nature of Matter The protons and the neutrons are found in the nucleus: Nuclear particles, nucleons or nucleons 2-1 The Nature of Matter electrons, The electrons, meanwhile, are in motion outside the nucleus ! 2-1 The Nature of Matter Electrons: occupy energy levels sometimes called shells or orbitals with the greatest energy are those whose shells are farthest from the nucleus 2-1 The Nature of Matter Orbitals: are the place where the electron (e-) of a given atom is most likely to be found ! which are outermost ( s and p orbitals ) determine an atoms properties 2-1 The Nature of Matter The Periodic Table: 2-1 The Nature of Matter The Periodic Table: was first proposed by Mendeleev (1871) is a system for classifying the elements, based on common properties is a system for classifying the elements, based on common properties columns are groups or families columns are groups or families rows are periods: one electron (e-) is added every time you move to the right rows are periods: one electron (e-) is added every time you move to the right 2-1 The Nature of Matter Using the Periodic Table The Symbol (shown as X) gives the name of the element first letter capitalized second letter, if required, lower case 2-1 The Nature of Matter Atomic Number (the A number) : identifies the elementidentifies the element is equal to the number of protons (whole number) in any given atom of that elementis equal to the number of protons (whole number) in any given atom of that element 2-1 The Nature of Matter also equals the number of electrons if the atom is neutral !also equals the number of electrons if the atom is neutral ! Atomic Number (the A number) : 2-1 The Nature of Matter Atomic Mass (the Z number): the weighted average of the masses of the isotopes of that element usually expressed as a decimal, rather than as a whole number 2-1 The Nature of Matter A quick way to show this information for a single atom: 2-1 The Nature of Matter Isotopes: are atoms of the same element, but with different massesare atoms of the same element, but with different masses differ in the number of neutrons, but the number of protons remains the same !differ in the number of neutrons, but the number of protons remains the same ! EXAMPLES: EXAMPLES: 12 C : 6 protons neutrons 13 C : 6 protons neutrons 14 C : 6 protons neutrons 2-1 The Nature of Matter Ions: are atoms of the same element, but which differ in chargeare atoms of the same element, but which differ in charge differ in the number of electrons, but the number of protons remains the same !differ in the number of electrons, but the number of protons remains the same ! EXAMPLES: EXAMPLES: Na (neutral) 11 protons electrons Na + (ion) 11 protons electrons Cl - (ion) : 17 protons electrons 2-1 The Nature of Matter Ionic Bonds: electrons are transferred ions (atoms or molecules with an overall net charge) are formed 2-1 The Nature of Matter Covalent Bonds: electrons are shared, travelling around both nuclei: (wow !)electrons are shared, travelling around both nuclei: (wow !) stable molecules of larger sizes (macromolecules) become possiblestable molecules of larger sizes (macromolecules) become possible 2-1 The Nature of Matter Single bonds share just 1 pair of e -Single bonds share just 1 pair of e - Double bonds share 2 pair of e -Double bonds share 2 pair of e - Triple bonds share 3 pair of e -Triple bonds share 3 pair of e - Covalent Bonds: 2-1 The Nature of Matter Polar Covalent Bonds: electrons are shared unequallyelectrons are shared unequally opposite ends of molecule carry small opposite charges (+ and -)opposite ends of molecule carry small opposite charges (+ and -) Examples include water (H 2 0), shown below:Examples include water (H 2 0), shown below: 2-1 The Nature of Matter