Chapter 3 – Classification of Matter

1. Chapter 3 – Classification of Matter • Elements – Distribution, Names, Symbols • Elements - Metals, Nonmetals, Metalloids • Diatomic Molecules • Chemical Formulas • Mixtures

2. Elements • Element:A substance that cannot be decomposed into simpler substances by chemical means. • Make up our chemical alphabet. • Over 100 known elements

3. Elements • Element:Our building block of all substances. • Numbered in order of increasing complexity • Elements through 92 are known to occur in nature. [with 4 exception Technetium (43), Promethium (61), Astatine (85), Francium (87)] • Above 92 only Plutonium (94) occur in nature. • Above 92 all elements must be synthesized in the laboratories in small quantities

4. Elements • Most substances can be decomposed into two or more simpler substance. • Water = Hydrogen and Oxygen • Sugar = Carbon, Hydrogen, and Oxygen • Salt = Sodium and Chloride

5. Elements • The smallest particle of an element that can exist is an atom, • which is also the smallest unit of an element that can enter into a chemical reaction. • Atoms are made up of subatomic particles that will be discussed later in the semester.

6. Distribution of Elements • Elements are distributed unequally in nature • Ten elements make up 99% of the mass of the Earths Crust, seawater, and atmosphere • Oxygen is about 50% of this mass • Two elements are liquids at room temperature • Bromine and Mercury • Eleven elements are gases • Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Helium, Neon, Argon, Krypton, Xenon, and Radon • All other elements are solids

7. Distribution of Elements • Elements are distributed unequally in nature • Figure a, shows the distribution in the glalaxies • Figure b, shows the distribution in Earths crust • Figure c, shows the distribution in Humans

8. Sources of Element Names Greek-Color • Iodine: from the Greek iodes meaning violet. Latin- Property • Fluorine: from the Latin fluere meaning to flow. The fluorine containing ore fluorospar is low melting. German- Color • Bismuth: from the German weisse mass which means white mass. Location • Germanium: discovered in 1866 by a German chemist. Famous- Scientists • Einsteinium: named for Albert Einstein.

9. Symbols of the Elements • Each element has an abbreviation. • Iodine is taken from Greek work iodes, meaning violet. • Bismuth is from German, weisse masse, white mass. • Germanium is due to it’s discovery by a German • Others are named in commemoration of famous scientist

10. Symbols of the Elements • Each element has an abbreviation – Symbols • Some (14) have single letter • The rest have 2 letters • The symbol stands for the element itself • For one atom of the element • For a particular quantity of the element • Rules. • Symbols have either one or two letters • If one letter – Capitalized • If two letters – First letter capitalized – second letter lower case

11. Rules governing symbols of the elements are: • Symbols have either one or two letters. • If one letter is used it is capitalized. H hydrogen C carbon • If two letters are used, only the first is capitalized. Ne neon Ba barium

12. Symbols of the Elements • Symbols and names are on the inside cover. • Possibly make flash cards to learn these symbols.

13. Metal, Nonmetals, and Metalloids

14. Metal, Nonmetals, and MetalloidsMetals • Most of the elements are metals • Solids at RT (except mercury) • Malleable – Can be hammered or rolled into sheets. • Ductile – Can be Drawn into wires • High Melting point • High density • Combine with non-metals to form ionic compounds • Often found as alloys – Homogenous mixtures

15. Metal, Nonmetals, and Metalloids • A few of the less reactive metals such as copper, silver and gold are found in the free state. • Metals can mix with each other to form alloys. • Brass is a mixture of copper and zinc. • Bronze is a mixture of copper and tin. • Steel is a mixture of carbon and iron.

16. Metal, Nonmetals, and Metalloids • Nonmetals • Low melting points and density • Generally poor conductors of heat and conductivity • Combine with one another to form molecular compounds • Metalloids • Properties are intermediate between metals and nonmetals • Some are raw material for semiconductor

17. Metalloids • boron • silicon • germanium • arsenic • antimony • tellurium • polonium

18. Compounds • Compound:A substance with a constant composition that can be broken down into elements by chemical processes. • Atoms in a compound are always • whole number ratios • Two types - molecular and ionic

19. Compounds • Molecule – The smallest uncharged individual unit of a compound formed from 2 or more atoms • Ion – Positively or negatively charged atom or group of atoms. • Held together by attractive forces from positively and negatively charged ions • Cation – Positively charged • Anion – Negatively charged

20. Compounds can be classified as molecular or ionic. Ionic compounds are held together by attractive forces between their positive and negative charges. Molecular compounds are held together by covalent bonds.

21. Diatomic Molecules • Special type of molecule • Contain 2 atoms – alike or different • Seven elements are diatomic molecules • Hydrogen - H2 • Oxygen - O2 • Nitrogen - N2 • Fluorine - F2 • Chlorine - Cl2 • Bromine - Br2 • Iodine - I2 • Need to know these!!!!

22. Occurrence of Diatomic Molecules

23. Chemical Formulas • Used as abbreviations for compounds • Shows the symbols and the ratio of the elements in a compound • H2O • Indicates 2 Hydrogens and one Oxygen • H2SO4 • Indicates 2 Hydrogens, 1 Sulfur, and 4 Oxygen

24. O2 H2O H2 • It does not contain free hydrogen, H2 or free oxygen, O2. • The H2 part of H2O means that 2 atoms of hydrogen are combined with one atom of oxygen in the water molecule. • Water has the formula H2O.

25. chemical formulas Serve as abbreviations of the names of compounds. CaCl2 calcium chloride

26. chemical formulas Tell which elements the compound is composed of and how many atoms of each element are present in a formula unit. CaCl2 calcium chlorine

27. chemical formulas Show the symbols of the atoms of the elements present in a compound. CaCl2 Ca calcium Cl chlorine

28. chemical formulas Show the ratio of the atoms of the elements present in a compound. CaCl2

29. Chemical Formulas • Formula of a compound contains the symbols of all the elements • Formula contains one atom of an element the number 1 subscript is left out • Formula contains more than one atom of the same element – the number is indicated as a subscript written to the right of the symbol of that atom • When a formula contains more than one group of atoms occur as a unit – a parentheses is place around the group with the number subscripted • Ca(NO3)2

30. indicates the element oxygen (O) indicates the element hydrogen (H) indicates 4 O atoms indicates 3 H atoms indicates the element phosphorous (P) Chemical Formulas H3PO4

31. indicates the element barium indicates three Ba atoms indicates the phosphate group composed of one phosphorous atom and four oxygen atoms Chemical Formulas Ba3(PO4)2

32. Chemical Formulas Formulas written as H2O, H2SO4, Ca(NO3)2 and C12H22O11show only the number and kind of each atom contained in the compound; they do not show the arrangements of the atoms in the compound or how they are chemically bonded to each other.

33. Concepts - Chapter 3 • Classify – elements, compounds, mixtures • Write symbols or name for common elements • Understand chemical formulas • Differentiate between atoms, molecules, ions • Know some characteristics of metals, nonmetals and metalloids • Recognize elements that occur as diatomic molecules