Ch 2: Atoms, Molecules, and Ions Modern view of atomic structure Review protons, neutrons, and electrons Every atom has an equal number of electrons and protons, no net electrical charge Where is most of the mass of an atom contained? What makes an atom of one element different from an atom of another element? What is an elements atomic number? o The number of protons in the nucleus of an atom of any particular element o Also number of electrons in a neutral atom o How elements are arranged on the periodic table What is mass number? o Total number of protons and neurons 𝑚𝑎𝑠𝑠 # o 𝑎𝑡𝑜𝑚𝑖𝑐 #𝑠𝑦𝑚𝑏𝑜𝑙 What are isotopes? o Atoms with the same number of protons different number of electrons o Same atomic numbers different mass numbers o Many times atomic number is omitted and isotopes are just written 12C or carbon12 Atomic weights How do elements occur in nature? o As mixtures of isotopes How do you determine average atomic mass? o (Percent abundance x mass of that isotope) + (Percent abundance x mass of that isotope)+ ….. =average atomic mass o Where is average atomic mass listed or found? o Maybe to practice problem on how to find AAM Periodic Table What can you tell me about how the periodic table is arranged? o Similar elements grouped into columns o Elements ordered in increasing atomic number o Alkali metals first column o Alkali earth metals second column o Halogens second to last column o Noble gasses last column o Metals are on the left side (hydrogen not a metal) o Nonmetals on right side o Sides divided by diagonal, step-like line, running from boron to astatine. These are called metalloids Rows are called periods Columns are called groups or families o Different labeling schemes are used to label these o Elements in the same group exhibit similar qualities Molecules and molecular compounds What is a diatomic molecule? o A molecule that is made up of two atoms o BrINClHOF What is the difference between empirical and molecular formulas? o Molecular formulas indicate the actual numbers and types and atoms in a molecule. Empirical formulas only give the relative number of atoms of each type in a molecule. Subscripts are always the smallest possible whole-number ratios. o C2H4 vs. CH2 o By knowing the molecular formula you can determine the empirical formula, the opposite is not true What is the structural formula? o Shows which atoms are attached to which within the molecule o Usually doesn’t depict the actual geometry of the molecule Various models are used to help visualize molecules Ions and Ionic compounds What are polyatomic ions? o Atoms joined as in a molecule, but they have a net positive of negative charge When atoms gain a charge what determines what charge they take? o Valence electrons o Want a full outer shell What is an ionic compound? o A compound that contains both positively and negatively charged ions o Sodium Chloride o Combination of metals and nonmetals Naming inorganic compounds How do we name type I binary compounds? o Name the ions, anion include –ide suffix o Metal and nonmetal, metal has known charge How do we name type II binary compounds? o Name both parts include roman numerals to indicate charge and –ide suffix on anion o Metal and nonmetal, metal’s charge is not known How do we name type III binary compounds? o Name each part using proper prefixes o Two nonmetals How do we name polyatomic anions containing oxygen? o Ending –ate or –ite o –ite assigned to polyatomic ion with lower oxygen content o Nitrate vs. nitrite How do we name acids containing anions whose names end in –ide? (don’t contain oxygen) o Change –ide ending to –ic and add hydro prefix How do we name acids containing anions whose names end in –ate or –ite? (do contain oxygen) o Change –ate to –ic and –ite to –ous Some simple organic compounds What are hydrocarbons? o Compounds that contain only carbon and hydrogen What are alkanes? o The most basic class of hydrocarbons, each carbon atom is bonded to four other atoms How do we name alkanes? o –ane ending, first four methane, ethane, propane, butane, then named for number of carbons What is an alcohol? o Occurs when an H atom of an alkane is replaced with an –OH group How do we name alcohols? o Add –ol ending When do we add a number out front when naming alcohols? o When the chain is 3 carbons or longer