Chapter 2: The Components of Matter

1. Chapter 2: The Components of Matter 2.5 The Atomic Theory Today 2.6 Elements: A First Look at the Periodic Table 2.7 Compounds: Introduction to Bonding

2. Clicker question #7 • The definition of an element is: • A substance that consists of only one type of atom. • A substance that can be broken down into simpler substances by physical or chemical means. • A substance that consists of multiple types of atoms. • A structure that consists of two or more atoms that are chemically bound together

3. Clicker question #7 • The definition of an element is: • A substance that consists of only one type of atom. • A substance that can be broken down into simpler substances by physical or chemical means. • A substance that consists of multiple types of atoms. • A structure that consists of two or more atoms that are chemically bound together

4. General features of the atom today. • The atom is an electrically neutral, spherical entity composed of a positively charged central nucleus surrounded by one or more negatively charged electrons. • The atomic nucleus consists of protons and neutrons.

5. Location in the Atom Name(Symbol) Relative Absolute(C)* Relative(amu)† Absolute(g) Proton (p+) 1+ +1.60218x10-19 1.00727 1.67262x10-24 Nucleus Neutron (n0) 0 0 1.00866 1.67493x10-24 Nucleus Outside Nucleus Electron (e-) 1- -1.60218x10-19 0.00054858 9.10939x10-28 Properties of the Three Key Subatomic Particles Charge Mass * The coulomb (C) is the SI unit of charge. † The atomic mass unit (amu) equals 1.66054x10-24 g.

6. Atomic Symbols, Isotopes, Numbers A X The Symbol of the Atom or Isotope Z X = Atomic symbol of the element A = mass number; A = Z + N Z = atomic number (the number of protons in the nucleus) N = number of neutrons in the nucleus Isotope = atoms of an element with the same number of protons, but a different number of neutrons

7. PROBLEM: • How many protons, neutrons, and electrons are in the following elements. What element symbols do Q and X represent? • 115 Q • 4120 X Sample Problem 2.2 Determining the Number of Subatomic Particles in the Isotopes of an Element

8. Clicker question #8 • Given 13153 Y. What element symbol does Y represent? • Na • I • Pt • Cs

9. Clicker question #8 • Given 13153 Y. What element symbol does Y represent? • Na • I • Pt • Cs

10. PROBLEM: Silver(Ag: Z = 47) has 46 known isotopes, but only two occur naturally, 107Ag and 109Ag. Given the following mass spectrometric data, calculate the atomic mass of Ag: Isotope Mass(amu) Abundance(%) 107Ag 106.90509 51.84 109Ag 108.90476 48.16 Sample Problem 2.3 Calculating the Atomic Mass of an Element Definition: amu or Da (atomic mass unit or Dalton) = 1/12 mass of 12C atom.

11. The Modern Reassessment of the Atomic Theory 1. All matter is composed of atoms. The atom is the smallest body thatretains the unique identityof the element. 2. Atoms of one element cannot be converted into atoms of another element in a chemical reaction. Elements can only be converted into other elements in nuclear reactions. 3. All atoms of an element have the same number of protons and electrons, which determines the chemical behavior of the element. Isotopes of an element differ in the number of neutrons, and thus in mass number. A sample of the element is treated as though its atoms have anaverage mass. 4. Compounds are formed by the chemical combination of two or more elements in specific ratios.

12. The modern periodic table. Similar chemical properties

13. The modern periodic table. Alkali metals

14. The modern periodic table. Alkaline earth metals

15. The modern periodic table. Halogens

16. The modern periodic table. Noble gases

17. Clicker question #9 • Using the periodic table, do you think Na and Cl have similar chemical properties? • Yes, I think they have similar chemical properties. • No, I do not think they have similar chemical properties. • I can not tell from the periodic table whether they have similar chemical properties. • This is a stupid question.

18. Clicker question #9 • Using the periodic table, do you think Na and Cl have similar chemical properties? • Yes, I think they have similar chemical properties. • No, I do not think they have similar chemical properties. • I can not tell from the periodic table whether they have similar chemical properties. • This is a stupid question.

19. Bonding – ionic compounds Formed from – the transfer of electrons from the atoms of one element to those of another Ions– charged particles Cation – positively charged ion Anion– negatively charged ion Ionic compound formation animation

20. PROBLEM: What monatomic ions do the following elements form? Sample Problem 2.4 Predicting the Ion and Element Forms (a) Sulfur (b) Rubidium (c) Barium

21. Formation of a covalent bond between two H atoms. Covalent bonds form when elements share electrons, which usually occurs between nonmetals.

22. Elements that occur as molecules. diatomic molecules tetratomic molecules octatomic molecules

23. Entities in covalent and ionic substances Most covalent substances consist of molecules No molecules exist in a sample of an ionic compound

24. Elements that are polyatomic. A polyatomic ion