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 of……empty 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 it’s 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 atom’s 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