1. Atoms, Molecules and Ions Atoms, Molecules and Ions

2. One of the main challenges of chemistry is to understand the connection between the macroscopic world that we experience and the microscopic world of atoms and molecules. - You must learn to think on the atomic level -

3. Scanning Tunneling Microscope (STM) – a special microscope used to "see" individual atoms. – it uses an electron from a tiny needle to probe the surface of the substance.

5. Dalton's Atomic Theory Each element is made up of tiny particles called atoms. The atoms of a given element are identical; the atoms of different elements are different in some fundamental way or ways. Chemical compounds are formed when atoms of different elements combine w/each other. A given compound always has the same relative numbers and types of atoms. Chemical reactions involve reorganization of the atoms -- changes in the way they are bound together. The atoms themselves are not changed in a chemical reaction.

6. The Structure of the Atom Atoms - are really small - are shaped like a sphere but is mostly empty inside. - at it's center is a space called the nucleus that contains 2 types of particles 1. proton 2. neutron - electron are spread around the nucleus

7. The nucleus is:  Small compared with the overall size of the atom.  Extremely dense; accounts for almost all of the atom’s mass. Nuclear Atom Viewed in Cross Section

8. Neutrons – found in the nucleus; no charge; virtually same mass as a proton. Protons – found in the nucleus; positive charge equal in magnitude to the electron’s negative charge. Electrons – found outside the nucleus; negatively charged. > # of protons = # of electrons * atoms are electrically neutral >Atomic number = # of protons - Defines an element because the atoms of a particular element have a specific number of protons. > Mass number = protons+ neutrons N 14 7 Nitrogen Atom

9. Two Isotopes of Sodium - Atoms with the same number of protons but different numbers of neutrons Isotopes - Atoms with the same number of protons but different numbers of neutrons.

10. - The elements are arranged by atomic number (the number above the element symbol) in horizontal rows called periods and in vertical columns known as groups or families, according to similarities in their chemical properties. - The periodic table was proposed by the Russian chemist Dimitri Mendeleev The Periodic Table

11. Copyright © Cengage Learning. All rights reserved 11 Special Names for Groups in the Periodic Table

12. Copyright © Cengage Learning. All rights reserved 12 Metals Versus Nonmetals

13. Molecules - formed when atoms react by sharing electrons forming covalent bonds. - most are composed of nonmetallic elements. > a molecule may contain atoms of the same element or atoms of 2 or more elements joined in a fixed ratio. * If the atoms belong to different elements, then the molecule is also known as a covalent compound.

14. An ion is an atom or group of atoms that has a net positive or negative charge (because they have either lost or gained electron) > cations - positive; atoms that lose electrons ; in most cases are derived from metals > anions - negative; atoms that gain electrons; in most cases are derived from nonmetals > Because anions & cations have opposite charges, they attract each other forming ionic compounds. This force of attraction between oppositely charged ions is called ionic bonding. Ions

15. - can be represented in several different ways. The simplest method is the chemical formula, in w/c the symbols for the elements are used to indicate the types of atoms present & subscripts are used to indicate the relative number of atoms. e.g. CO 2 => contains 1 atom of carbon & 2 atoms of oxygen Covalent & Ionic Compounds

16. Binary Ionic Compounds  Metal—nonmetal Naming Compounds Binary Compounds  Composed of two elements  Ionic and covalent compounds included Binary Covalent Compounds  Nonmetal—nonmetal

17. > Review & familiarize yourself w/the names of the elements on the Periodic Table & their corrresponding symbols <

18. Flowchart for Naming Binary Compounds (Fig. 3.10)

19. 1.The cation is always named first and the anion second. 2.A monatomic cation takes its name from the name of the parent element. 3.A monatomic anion is named by taking the root of the element name and adding – ide. Binary Ionic Compounds (Type I) Examples: KClPotassium chloride MgBr 2 Magnesium bromide CaOCalcium oxide

20. Metals in these compounds form more than one type of positive charge. Charge on the metal ion must be specified. Roman numeral indicates the charge of the metal cation. Transition metal cations usually require a Roman numeral. Binary Ionic Compounds (Type II) Examples: CuBrCopper(I) bromide FeSIron(II) sulfide PbO 2 Lead(IV) oxide

21. Review & familiarize yourself w/the Common Polyatomic Ions (see Table 3.5) Examples of compounds containing polyatomic ions: NaOHSodium hydroxide Mg(NO 3 ) 2 Magnesium nitrate (NH 4 ) 2 SO 4 Ammonium sulfate Polyatomic Ions

22. Prefixes Used to Indicate Number in Chemical Names

23. Formed between two nonmetals. 1.The first element in the formula is named first, using the full element name. 2.The second element is named as if it were an anion. *A monatomic anion is named by taking the root of the element name and adding –ide.* 3.Prefixes are used to denote the numbers of atoms present. 4.The prefix mono- is never used for naming the first element. Binary Covalent Compounds (Type III) Examples: CO 2 Carbon dioxide SF 6 Sulfur hexafluoride N 2 O 4 Dinitrogen tetroxide

24. Acids can be recognized by the hydrogen that appears first in the formula—HCl. Molecule with one or more H + ions attached to an anion. Acids

25. Flowchart for Naming Acids

26. If the anion does not contain oxygen, the acid is named with the prefix hydro– and the suffix –ic. Examples: HClHydrochloric acid HCNHydrocyanic acid H 2 SHydrosulfuric acid Acids

27. If the anion does contain oxygen:  The suffix –ic is added to the root name if the anion name ends in –ate. Examples: HNO 3 Nitric acid H 2 SO 4 Sulfuric acid HC 2 H 3 O 2 Acetic acid Acids

28. If the anion does contain oxygen:  The suffix –ous is added to the root name if the anion name ends in –ite. Examples: HNO 2 Nitrous acid H 2 SO 3 Sulfurous acid HClO 2 Chlorous acid Acids