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Unit B Chemical Reactions 4.1: Matter • Matter is anything that has mass and takes up space • Matter does not include any form of energy, such as light, heat, and sound. • Many substances have been classified according their physical and chemical properties Copyright © 2010 Pearson Canada Inc. B-1 Properties of Matter • A physical property is a property that describes the physical appearance and composition of a substance. • A chemical property is a property that describes the ability of a substance to change into a new substance or substances. • Check table 4.1 & 4.2 Pg 142 Copyright © 2010 Pearson Canada Inc. B-2 Pure Substances and Mixtures • All forms of matter can be classified as either a pure substance or a mixture, based on their physical and chemical properties. Copyright © 2010 Pearson Canada Inc. B-3 A pure substance • made up of only one kind of matter. • has a unique set of properties, such as colour, hardness, melting point, and conductivity. • A pure substance is either an element or a compound. Copyright © 2010 Pearson Canada Inc. B-4 • An element is a substance that cannot be broken down into any simpler substance by chemical means. • E.g. Iron, oxygen, and neon are examples of elements. • A compound is a pure substance that is made from two or more elements that are combined together chemically. • E.g. methane (CH4) contains the elements carbon and hydrogen. Copyright © 2010 Pearson Canada Inc. B-5 A mixture • is a combination of pure substances • Properties of mixtures vary • Two main types of mixtures Copyright © 2010 Pearson Canada Inc. B-6 Types of Mixtures • A homogeneous mixture is a mixture that looks the same throughout and the separate components are not visible. • Solutions are homogeneous mixtures. • iced tea is a solution of sugar and other substances dissolved in water Copyright © 2010 Pearson Canada Inc. B-7 • A heterogeneous mixture is one in which different parts of the mixture are visible. • a suspension, a cloudy mixture in which tiny particles of one substance are held within another substance. • Salad dressing is an example of a suspension • a mechanical mixture, may contain several solids combined together, such as in a chocolate-chip cookie. Copyright © 2010 Pearson Canada Inc. B-8 Classification of Matter Tree Diagram Copyright © 2010 Pearson Canada Inc. B-9 Matter And Atoms • All matter is made up of tiny particles called atoms. An atom is the smallest part of an element that has all the element’s properties. • Gold and silver are elements. Atoms of gold are similar to each other but different from atoms of silver. Copyright © 2010 Pearson Canada Inc. B - 10 Dalton’s Atomic Theory • Atomic theory is the study of the nature of atoms and how atoms combine to form all types of matter. • Atoms are the smallest indivisible particles of matter • Each element has its own unique kind of atom. • Atoms of different elements vary in mass, volume, and reactivity and are in continuous motion. • Atoms combine to form compound/molecules Copyright © 2010 Pearson Canada Inc. B - 11 Subatomic Particles of matter • There are three subatomic particles, protons, neutrons, and electrons that make atoms. • Electrons and protons have an electric charge. Protons have a positive charge of 1+. Electrons have a negative charge of 1• Neutrons are neutral. • The masses of protons and neutrons are almost 2000 times greater than the mass of electrons • Copy Table 4.3 Properties of Subatomic Particles Copyright © 2010 Pearson Canada Inc. B - 12 An Atom Copyright © 2010 Pearson Canada Inc. B - 13 Representing an Atom • The basic arrangement of the nucleus and electrons in a atom is typical of all atoms e.g. sulphur. • The atoms of every element have a unique number of protons, called atomic number. • A Bohr-Rutherford diagram is an illustration of an atom that shows the arrangement and number of electrons in each shell, with number of protons and neutron in the nucleus . Copyright © 2010 Pearson Canada Inc. B - 14 Bohr-Rutherford Diagram • The electrons surround the nucleus in shells. Each shell has a specific energy level. • The innermost shell can hold two electrons at most. • The next two shells can hold up to eight electrons each. • The outermost shell of an atom is called the valence shell and contains the valence B - 15 electrons. Copyright © 2010 Pearson Canada Inc. Sulphur Atom Copyright © 2010 Pearson Canada Inc. B - 16 Bohr Diagrams of First 20 Elements from the Periodic Table Copyright © 2010 Pearson Canada Inc. B - 17 The Periodic Table of Elements • The periodic table contains a set of symbols to represent the elements, laid out in a specific pattern • Dmitri Mendeleev was the first person to create a table that organized all the elements logically, including those that were not discovered at the time. Copyright © 2010 Pearson Canada Inc. B - 18 Characteristics of the Periodic Table • The horizontal rows of the periodic table are called periods. • The vertical columns are called families (or groups). • Elements in the same family in the periodic table have similar physical and chemical properties • Metals are on the left and in the centre of the table. • Non-metals are located on the right-hand side of the table. B - 19 Copyright © 2010 Pearson Canada Inc. • Metals are separated from non-metals by a staircase of elements called the metalloids. Copyright © 2010 Pearson Canada Inc. B - 20 Metals and non Metals • Metals are good conductors of heat and electricity. • they are ductile and malleable. • they are shiny and usually silver coloured, and all but one are solids at room temperature. • Nonmetals are not metals, and they generally are poor conductors of heat. • At room temperature, some non-metals are solids, some are gases, and one, bromine, is a liquid. • Mercury is a metal, but it is liquid at room temperature. Copyright © 2010 Pearson Canada Inc. B - 21 Dmitri Mendeleev Copyright © 2010 Pearson Canada Inc. B - 22 Periodic Table Copyright © 2010 Pearson Canada Inc. B - 23 Chemical Families • alkali metals (group 1):metals that react easily with water and with oxygen in the air. hydrogen is not an alkali metal • alkaline earth metals (group 2): harder and less reactive than group 1 metals. combines easily with other atoms. • halogens (group 17): most reactive non-metals • noble gases (group 18): unreactive gases does not combine easily with other atoms. Copyright © 2010 Pearson Canada Inc. B - 24 Chemical Families from the Periodic Table Copyright © 2010 Pearson Canada Inc. B - 25 Elements on the Periodic Table • The atomic number: is the number of protons in an atom of an element. E.g. atomic number of copper is 29 • The atomic mass is the average mass of an atom of that element. atomic mass of hydrogen is about 1, copper is 63.55. • mass of a copper atom is about 64 times the mass of a hydrogen atom. Copyright © 2010 Pearson Canada Inc. B - 26 Ion Charge: • An ion is an atom or group of atoms with a negative charge or a positive charge. • Atoms of some elements can gain or lose electrons during chemical change. • An atom that gains electrons becomes a negatively charged ion. • An atom that loses electrons becomes a positively charged ion. Copyright © 2010 Pearson Canada Inc. B - 27 Copper from the Periodic Table Copyright © 2010 Pearson Canada Inc. B - 28