1.3-PURE-SUBSTANCES-AND-MIXTURES.pdf

Lesson 1.3 Pure Substances and Mixtures General Chemistry 1 Science, Technology, Engineering, and Mathematics The world offers variety in terms of materials that can be encountered on a daily basis. 2 There are materials that are pu...

Lesson 1.3 Pure Substances and Mixtures General Chemistry 1 Science, Technology, Engineering, and Mathematics The world offers variety in terms of materials that can be encountered on a daily basis. 2 There are materials that are pure in terms of its composition, like water. 3 Others are combinations of two or more substances. For example, the atmosphere is made up of different gases. 4 How can matter be classified? 5  Learning Objectives At the end of the lesson, you should be able to do the following: Differentiate pure substances from mixtures. Categorize pure substances as elements and compounds. Enumerate the classifications of mixtures. 6 Classifications of Matter Matter may be classified according to their state or phase. solid liquid gas 7  Classifications of Matter Matter may be classified according to their properties. physical properties - observable even without changing the composition of matter ○ color ○ size ○ shape 8  Classifications of Matter Matter may be classified according to their properties. chemical properties - observed once a material undergoes a chemical reaction ○ flammability ○ reactivity ○ biodegradability 9  Classifications of Matter Matter may be classified according to their composition. pure substances ○ matter have a fixed or definite composition mixtures ○ combinations of two or more substances 10 How do pure substances and mixture compare? 11  Pure Substances a kind of matter with a definite or fixed composition made up of a specific number of atoms or groups of atoms that are combined through a chemical reaction has definite physical and chemical properties 12  Pure Substances classified into elements and compounds atoms of an molecules of an molecules of a element element compound 13  Pure Substances: Elements Element the simplest form of matter made up of only one kind of atom Cu atoms in copper wire elements of different kinds also differ in the atoms that make them up Fe atoms in iron 14  Pure Substances: Elements Element cannot be decomposed into simpler forms by physical or chemical means react with one another to form a new substances 118 elements known to exist arranged in the periodic table of elements ○ 94 of these are naturally occurring ○ 24 of these are synthetic 15 Pure Substances: Elements The periodic table of elements is the arrangement of all known 16 elements according to their chemical properties.  Pure Substances: Elements Periodic Table of Elements a useful tool that can help in identifying elements that exhibit similar properties classifies elements into 3 categories: ○ metals - leftmost of the periodic table ○ nonmetals - rightmost of the periodic table ○ metalloids - staircase-like line between metals and nonmetals 17  Pure Substances: Elements Metals general properties: ○ solid at room temperature silver tungsten ○ lustrous ○ malleable ○ ductile ○ heat/electricity conductors platinum gold 18 Did You Know? Mercury is the only metal that is liquid at room temperature. It is a shiny, silvery liquid metal that forms beads due to its high surface tension. Mercury is also known as quicksilver due to its appearance and mobility. 19  Pure Substances: Elements Nonmetals general properties: ○ opposite of metals ○ gaseous or dull solids sulfur ○ poor conductors of heat and electricity oxygen gas 20 Did You Know? Bromine is the only nonmetal that exists in liquid form at room temperature. 21  Pure Substances: Elements Metalloids/Semimetals exhibit properties of both metals and nonmetal conducts heat and electricity but not as good as how metals act as conductors Silicon and germanium are metalloids that are widely used semiconductors in the manufacture of computer chips. 22 How can elements be broken down into much simpler forms? 23  Pure Substances: Compounds Compounds composed of two or more different elements that are combined in a fixed ratio by a chemical Water (H2O) is formed when two reaction hydrogen atoms (H) combined with one oxygen atom (O). 24  Pure Substances: Compounds Many compounds are found in the environment. Some compounds are formed when an element reacts with another element. Some compounds are products of chemical reactions between two or more compounds. 25  Pure Substances: Compounds Chemical bonds cannot be broken easily Unlike elements, compounds can be broken down into simpler forms by chemical means In water electrolysis, an electric current is passed through water to separate its components to oxygen and hydrogen. 26  Pure Substances: Compounds The properties of elements that make up a compound are different from the properties of the compound formed. ○ sodium chloride (NaCl) or table salt - one Na atom and one Cl atom ○ its constituent elements are harmful and toxic 27  Pure Substances: Compounds may be classified according to the specific elements present ○ organic compounds - contains carbon and hydrogen ex. carbohydrates, proteins, lipids, etc. 28  Pure Substances: Compounds may be classified according to the specific elements present ○ inorganic compounds - do not contain carbon- hydrogen bonds ex. CO2, H2O, table salt (NaCl) 29 How do compounds differ from elements? 30  Mixtures consist of two or more pure substances that are combined physically no chemical reaction between the components Seawater is a mixture of components retain their dissolved salts and water. characteristic properties when mixed together 31  Mixtures each component has the same chemical makeup it had before the mixture is formed do not have definite proportions and definite properties properties depend on the substances that are present in it may be further classified as homogeneous or heterogeneous 32  Homogeneous Mixtures Homogeneous Mixture consists of substances that are evenly distributed all throughout the components cannot be distinguished from each other by the naked eye also known as solution 33  Homogeneous Mixtures Solution composed of two components: ○ solute - the substance that is dissolved by another substance; exists in smaller amounts ○ solvent - the dissolving medium in which the solute dissolves; In a salt solution, the solute is the salt while the most abundant solvent is water. 34  Homogeneous Mixtures Solution soluble - when substances dissolve in a given solvent miscible - when liquids are soluble in each other at all proportions In a salt solution, salt is soluble in water. 35 Homogeneous Mixtures Solutes dissolved in a solvent when the solute particles are pulled away from one another and the solvent particles continue to surround it until they are evenly spread out. 36  Homogeneous Mixtures may be solid, liquid or gas Wine is a liquid solution of Steel is a solid solution, or an alcohol and water. alloy, made up of iron and carbon. 37  Heterogeneous Mixtures Heterogeneous Mixture consists of substances that are not evenly distributed all throughout the components can be distinguished from each other by the naked eye can be further classified as colloids or suspensions 38  Heterogeneous Mixtures: Colloids Colloids a heterogeneous mixture with particles that are bigger than those in a solution but smaller than those in a suspension particles do not settle at the bottom even after being left to stand for a long time Milk is an example exhibit Tyndall effect of a colloid. 39  Heterogeneous Mixtures: Colloids Tyndall Effect the phenomenon wherein light is scattered. The Tyndall effect. 40  Heterogeneous Mixtures: Colloids Suspensions a heterogeneous mixture with suspended particles that are large enough to be seen by the naked eye particles settle at the bottom of the container due to gravity Boba milk is an example of a suspension. 41 Remember To easily distinguish the types of mixtures, always refer to the uniformity of its appearance. Homogeneous mixtures have a uniform appearance while heterogeneous mixtures are not uniform in terms of its appearance. 42  Check Your Understanding Classify the following materials either as an element, a compound, or a mixture. 2. 3. mossy zinc mayonnaise baking soda 43  Let’s Sum It Up! Matter may be classified according to their composition: pure substances and mixtures. A pure substance is a kind of matter with a definite or fixed composition. A mixture is a kind of matter that consists of two or more substances that are combined physically. 44  Let’s Sum It Up! Pure substances are classified as elements or compounds. ○ An element is the simplest form of matter made up of one type of atom. ○ A compound is made up of different types of atoms that are combined chemically. 45  Let’s Sum It Up! Mixtures are classified as homogeneous mixtures or heterogeneous mixtures. ○ A homogeneous mixture consists of particles that are evenly distributed all throughout. ○ A heterogeneous mixture consists of particles that are not evenly distributed all throughout. 46 Challenge Yourself How can you easily distinguish homogeneous mixtures from heterogeneous mixtures? 47