TOPIC II Describing matter

They are the fundamental building block of matter. Atoms and Molecules They are the fundamental building block of matter. Matter is composed of tiny particles called atoms. Atom: smallest part of an element that is still that element. Molecule: Two or more atoms joined and acting as a unit. Copyright © Cengage Learning. All rights reserved

Iron (Fe), aluminum (Al), oxygen (O2), and hydrogen (H2) Element A substance that cannot be broken down into other substances by chemical methods. Examples: Iron (Fe), aluminum (Al), oxygen (O2), and hydrogen (H2) All of the matter in the world around us contains elements. Copyright © Cengage Learning. All rights reserved

Elements Which element is most abundant in both Earth’s crust and in the human body?

Elements Symbols consists of one or two letters, with the first letter capitalized. Often derived from the English name. You will need to know these symbols and to learn others.

Introduction to the Periodic Table The vertical columns of the periodic table are called groups, or families. Each group contains elements with similar chemical properties. The horizontal rows of elements in the periodic table are called periods. Physical and chemical properties change somewhat regularly across a period.

Types of Elements Metals A metal is an element that is a good electrical conductor and a good heat conductor. Properties of metals most are solids at room temperature malleable - they can be hammered or rolled into thin sheets ductile - they can be drawn into a fine wire conduct electricity and heat well

Types of Elements Gold, copper, and aluminum are metals

Properties of nonmetals many are gases solids are brittle Types of Elements Nonmetals A nonmetal is an element that is a poor conductor of heat and electricity. Properties of nonmetals many are gases solids are brittle poor conductors of heat and electricity

Types of Elements Various nonmetal elements (a) carbon, (b) sulfur, (c) phosphorus, and (d) iodine

Types of Elements Metalloids A metalloid is an element that has some characteristics of metals and some characteristics of nonmetals. Properties of metalloids all metalloids are solids at room temperature. semiconductors of electricity.

He Types of Elements Noble Gases elements in Group 18 of the periodic table generally unreactive gases at room temperature He

Water (H2O), carbon dioxide (CO2), table sugar (C12H22O11) Compound A substance composed of a given combination of elements that can be broken down into those elements by chemical methods. Examples: Water (H2O), carbon dioxide (CO2), table sugar (C12H22O11) A compound always contains atoms of different elements. A compound always has the same composition (same combination of atoms). Copyright © Cengage Learning. All rights reserved

How many of the following are compounds? H2O, N2, NaOH, MnO2, H2 Concept Check How many of the following are compounds? H2O, N2, NaOH, MnO2, H2 Three – H2O, NaOH, MnO2 Five – All of the substances are compounds. Compounds always contain atoms of different elements. Copyright © Cengage Learning. All rights reserved

Always have the same composition and are formed by chemical processes. Pure Substances Always have the same composition and are formed by chemical processes. Either elements or compounds. Examples: Pure water (H2O), carbon dioxide (CO2), hydrogen (H2), gold (Au) Copyright © Cengage Learning. All rights reserved

Have variable composition. Examples Wood, wine, coffee, granite Mixtures Have variable composition. Examples Wood, wine, coffee, granite Can be separated into pure substances: elements and/or compounds using physical processes.

Having visibly indistinguishable parts. A solution. Homogeneous Mixture Same throughout. Having visibly indistinguishable parts. A solution. Does not vary in composition from one region to another. Apple Juice Cranberry Juice Orange Juice

Homogeneous Mixture – Examples Air around you Brass Table salt stirred into water

Heterogeneous Mixture Having visibly distinguishable parts. Contains regions that have different properties from those of other regions.

Heterogeneous Mixture – Examples Oil and vinegar dressing Sand stirred into water Copyright © Cengage Learning. All rights reserved

Classification of Matter

Pure water Gasoline Jar of jelly beans Soil Copper metal Concept Check Which of the following is a homogeneous mixture? Pure water Gasoline Jar of jelly beans Soil Copper metal gasoline Copyright © Cengage Learning. All rights reserved

Oxygen and Helium in a SCUBA tank ____ Classify as Pure Substance (PS), Homogeneous (HO) or Heterogeneous Mixture (HE) Oxygen and Helium in a SCUBA tank ____ Oil and vinegar salad dressing ____ Table salt (NaCl)____ Maple Syrup____ Pure water____ Gasoline____ Jar of jelly beans____ Soil____ Copper metal____ Copyright © Cengage Learning. All rights reserved