1. Elements and Compounds

2. Outline Elements Distribution of the elements Names of the elements
Symbols of the elements
Introduction to the periodic table
Elements in their natural states
Diatomic molecules
Compounds
Chemical Formulas

3. Element
An element is a fundamental or elementary substance that cannot be broken down into simpler substances by chemical means.

4. All known substances are formed
from various combinations of just
over 100 elements.

5. Atom
The smallest particle of an element that can exist.
The smallest unit of an element that can enter
into a chemical reaction.

9. Element names come from Greek, Latin, German, locations, and famous scientists
Examples: Iodine: from the Greek iodes meaning violet. Fluorine: from the Latin fluere meaning to flow. Bismuth: from the German weisse mass which means white mass. Germanium: discovered in 1866 by a German chemist. Einsteinium: named for Albert Einstein.

11. Physical Properties of Metals
Most elements are metals. Most metals are solid at room temperature. Metals are good conductors of heat and electricity. Metals are malleable (they can be rolled or hammered into sheets). Metals have high luster (they are shiny).
Metals are ductile (they can be drawn into wires).
Most metals have a high melting point.
Metals have high densities.

12. Chemical Properties of Metals
Metals have little tendency to combine with each other to form compounds. Many metals readily combine with nonmetals to form ionic compounds.
They can combine with halogens, sulfur, oxygen …
In nature, minerals are formed by combinations of the more reactive metals with other elements.

13. More Chemical Properties of Metals
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.

14. Physical Properties of Nonmetals
Lack luster (they are dull)
Have relatively low melting points
Have low densities.
Poor conductors of heat and electricity
At room temperature, carbon, phosphorous, sulfur, selenium, and iodine are solids.

15. Metalloids have properties that are intermediate between metals and nonmetals

16. The Metalloids
boron
silicon
germanium
arsenic
antimony
tellurium
polonium

18. N 7 The periodic table was designed by Dimitri Mendelev in 1869.
In the table each element’s symbol is placed inside of a box.
Above the symbol of the element is its atomic number. N 7

19. The elements are arranged in order of increasing atomic number.
Elements with similar chemical properties are organized in columns called families or groups . He Ne
These elements are known as the noble gases. They are nonreactive. Ar Kr Xe Rn

20. Most substances around us are mixtures or compounds
Most substances around us are mixtures or compounds. Some elements are found in pure form such as copper, gold and silver.

21. Most substances around us are mixtures or compounds
Most substances around us are mixtures or compounds. Air is composed mainly of nitrogen and oxygen gases. Nitrogen and oxygen are composed of tiny two atom molecules of N2 and O2.
These are both examples of diatomic molecules.
A diatomic molecule contains exactly two atoms of the same or different elements.

23. A compound is a distinct substance that contains two or more elements combined in a definite proportion by weight.

24. Compounds can be decomposed chemically into simpler substances–that is, into simpler compounds or elements.
Elements cannot be decomposed into simpler substances.
Atoms of the elements that constitute a compound are always present in simple whole number ratios. They are never present as fractional parts.

25. There are two types of compounds: molecular and ionic.

26. A molecule is the smallest uncharged individual
unit of a compound formed by the union of two
or more atoms.

27. A water molecule consists of two hydrogen atoms and one oxygen atom.
If it is subdivided the water molecule will be destroyed and hydrogen and oxygen will be formed.

28. An ion is a positively or negatively charged atom or group of atoms.

29. A cation is a positively charged ion.
3.5

30. An anion is a negatively charged ion.
3.5

31. Ionic compounds are held together by attractive forces between positively and negatively charged ions.

32. Sodium Chloride
Sodium chloride is a colorless crystalline ionic substance.
It is 39.3% sodium and 60.7% chlorine by mass.
The solid does not conduct electricity.
Passing an electric current through the molten salt produces solid sodium and gaseous chlorine.

33. Sodium Chloride
The ultimate particles of sodium chloride are positively charged sodium ions and negatively charged chloride ions.

34. Sodium Chloride
The crystalline structure of sodium chloride is held together by the attractive forces between the positive sodium ions and the negative chloride ions

35. The actual chemical formulas of ionic compounds express the smallest whole number ratio that exists between the cations and the anions.
Sodium chloride and other ionic compounds consist of large aggregates of cations and anions.
The formula NaCl does not mean that a molecule of NaCl exists.
The formula NaCl means that the ratio of sodium to chlorine in a sodium chloride crystal is one to one.

36. The ratio of Na+ to Cl- is 1:1

37. 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.

38. NaCl Indicates the element Indicates the element sodium (one atom)
chlorine (one atom)

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

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