1. Chemistry

2. Atoms PART 1

3. The artist that designed this image created it using thousands of tiny spots of color. Matter is like that, too. Matter is anything that takes up space and has mass. There are 4 phases of matter: solid, liquid, gas, and plasma. The tiny objects that make up all matter are called atoms.

4. Atoms are made up of even smaller particles. Protons (+ charge) Neutrons (no charge) Electrons (- charge)

5. Most of the mass of an atom is found in the central part of the atom, called the nucleus. The nucleus of an atom is made up of protons and neutrons. These particles are packed very tightly together in the nucleus.

6. An element can be identified on the Periodic Table by the number of protons in its nucleus. This is called its atomic number. Each element has its own unique atomic number.

7. Electrons are found outside the nucleus in the electron cloud. They circle the nucleus very, very quickly. Electrons are very small and have almost no mass. The number of electrons (-) in the electron cloud of an atom is always equal to the number of protons (+) in the nucleus of that atom.

8. Since atoms in nature have the same number of protons and electrons, the number of positive charges equals the number of negative charges. The opposite charges cancel each other out. Therefore, the whole atom has no overall charge.

9. Isotopes We have said that the number of protons (+ charges) in an atom’s nucleus must equal the number of electrons (- charges) in the cloud to have a neutral atom. However, since the neutron has no charge, sometimes an atom will have more or fewer of them in the nucleus and can still remain neutral.

10. The weight of an atom (atomic mass) is found by adding the particles in its nucleus (protons and neutrons). Isotopes of an element will all have the same atomic number (# of protons) but they will have different atomic weights or “mass numbers”.

11. Can you explain this cartoon?

12. Periodic Table PART 2

13. Chemists have organized all the known elements into the Periodic Table.

14. Why is the Periodic Table important to me? The periodic table is the most useful tool to a chemist. It organizes lots of information about all the known elements.

15. Elements are substances that are the building blocks of matter. An element is made up of one kind of atom. An atom is the smallest particle into which an element can be divided and still have the properties of that element. A molecule is two or more atoms put together that still have the properties of a particular substance.

16. To make molecules, you must have elements. Elements are made of atoms. While the atoms may have different weights and organization, they are all built the same way. Elements can not be broken down into smaller substances by chemical or physical means. Elements contain one type of atom.

17. Dmitri Mendeleev: Father of the Table HOW HIS WORKED… Put elements in rows by increasing atomic mass. Put elements in columns by the way they reacted. SOME PROBLEMS… He left blank spaces for what he said were undiscovered elements. (Turned out he was right!) He broke the pattern of increasing atomic mass to keep similar reacting elements together.

18. The Current Periodic Table Now the elements are put in rows by increasing ATOMIC NUMBER!! The horizontal rows are called periods and are labeled from 1 to 7. The vertical columns are called groups or families and are labeled from 1 to 18.

19. Groups…Here’s Where the Periodic Table Gets Useful!! Elements in the same group have similar chemical and physical properties!! (Mendeleev did that on purpose.) Why?? They have the same number of valence electrons for bonding. They will form the same kinds of ions and chemical bonds.

20. Families on the Periodic Table Columns are also grouped into families. Families may be one column, or several columns put together. Families have names rather than numbers. (Just like your family has a common last name.)

21. Hydrogen Hydrogen belongs to a family of its own. Hydrogen is a diatomic, reactive gas. Hydrogen is promising as an alternative fuel source for automobiles. Hydrogen was involved in the explosion of the Hindenburg.

22. Alkali Metals 1 st column on the periodic table (Group 1) not including hydrogen. Very reactive metals, always combined with something else in nature (like in salt). Soft enough to cut with a butter knife.

23. Alkaline Earth Metals Second column on the periodic table. (Group 2) Reactive metals that are always combined with nonmetals in nature. Several of these elements are important mineral nutrients (such as Mg and Ca). Beryllium is a key element in many gemstones.

24. Transition Metals Elements in groups 3-12 Less reactive, harder metals Includes metals used in jewelry and construction. Metals used “as metal.”

25. Halogens Elements in group 17 Very reactive, volatile, diatomic, nonmetals Always found combined with other element in nature Used as disinfectants and to strengthen teeth.

26. The Noble Gases Elements in group 18 VERY nonreactive, monatomic gases Used in lighted “neon” signs Have a full valence shell

27. Metals, Non-Metals, and Metalloids PART 3

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29. Metals All metals have 4 characteristics: – They are shiny (“have metallic luster”). – They are malleable (can be hammered into thin sheets). – They are ductile (can be pulled into thin wires). – They are good conductors of heat and electricity.

30. The reactivity of metals (or how easily they form bonds with other elements) tends to decrease from left to right across the rows of the periodic table and increases from top to bottom of the columns. Less reactive More reactive

31. Nonmetals Characteristics of Nonmetals: – Poor conductors of heat and electricity – Gases or brittle solids at room temperature – Solid nonmetals are dull and brittle Fluorine Sulfur

32. Metalloids Share properties of metals and nonmetals The most useful property of metalloids is as semi- conductors because of their varying ability to conduct electricity They are found on the periodic table touching either side of the zigzag line

33. Element Bonding PART IV

34. How Elements Bond Atoms bond by: Loosing electrons Gaining electrons By pooling electrons Or by sharing electrons

35. Ionic Bonds (Metals and Non-Metals) 1. An atom that is no longer neutral because it has gained or lost an electron is called an ion. 2. An ionic bond forms when positive and negative ions attract each other (they get “stuck together” like the positive and negative ends of a magnet). a. Sodium chloride is formed from sodium ions and chlorine ions. b. Two or more elements that are chemically bonded form a compound. 3. Some atoms can gain or loose more than one electron when they form ions.

36. Metallic Bonds (metals bonded together) Metallic Bonds form when metal atoms share their pooled electrons. A.Outermost electrons wander freely through metal. Metal consists of cations held together by negatively-charged electron "glue.“ B.Free electrons can move rapidly in response to electric fields, hence metals are a good conductor of electricity. C.Free electrons can transmit kinetic energy rapidly, hence metals are good conductors of heat. D.The layers of atoms in metal are hard to pull apart because of the electrons holding them together, hence metals are tough. But individual atoms are not held to any other specific atoms, hence atoms slip easily past one another. Thus metals are ductile and malleable. Metallic bonding is the basis of our industrial civilization.

37. Covalent Bonds (non-metals bonded together) A covalent bond forms between atoms that share electrons. 1. Atoms sharing electrons form a neutral particle called a molecule. a. Covalently bonded compounds are called molecular compounds. b. No electrons are gained or lost-- (they are shared). 2. Two pairs of electrons are involved in a double bond.

38. Polar Bonds A Polar Bond occurs when electrons are unevenly shared. 1. Polar molecules such as water have two opposite ends, or poles, like a magnet. 2. Non-polar bonds form between atoms of the same element.

39. Chemical Bonding Ionic Bonds Non-metal bonded to metal Called a compound Gain or Loose Electrons Metallic Bonds Metal bonded to metal -- Pooled Electrons Covalent Bonds Non-metal bonded to non-metal Called a molecule Share Electrons Copy this into your notes

40. Elements, Symbols, And Formulas PART V

41. Element Symbols Symbols are used to represent atoms and compounds. 1. Elements are represented by a one- two- or three-letter symbol. C carbon Au gold Fe iron 2. Compounds are described using element symbols and numbers. C 6 H 12 O 6 glucose H 2 O water

42. Chemical Formulas 3. In the formula H 2, the small 2 after the H is called a subscript, and indicates the number of atoms of hydrogen that are in the molecule.

43. Chemical Formulas 4. A chemical formula is a combination of chemical symbols and numbers. a. It tells which elements are present and how many atoms of each element are present. b. No subscript means that only one atom of that element is present.