GEN-chem-week-2 PDF

SCIENCE, TECHNOLOGY, ENGINEERING, AND 12 MATEMATICS What is Matter? Matter Nestor Oliveros Jr. SPST-I MELC. Recognize that substances are made up of smaller...

SCIENCE, TECHNOLOGY, ENGINEERING, AND 12 MATEMATICS What is Matter? Matter Nestor Oliveros Jr. SPST-I MELC. Recognize that substances are made up of smaller particles STEM_GC11MP Ia-b-1 Objectives 1. Define matter and explain how it is composed of building blocks known as "atoms.“ 2. To describe the solid, liquid and gas phases. Objectives 3. Explain the difference between a pure substance and a mixture. 4. Explain the difference between an element and a compound. 5. Explain the difference between a homogeneous mixture and a heterogeneous mixture. What is Matter? What is Matter? Matter is anything that has mass and volume (takes up space). Matter includes atoms and anything made up of atoms, but not other energy phenomena or waves such as light or sound. What is Matter? While this simple definition is easily applied, the way people view matter is often broken down into two characteristic scales: the macroscopic and the microscopic. What is Matter? The macroscopic scale is the scale on which objects or phenomena are large enough to be visible practically with the naked eye, without magnifying optical instruments. What is Matter? Everything one can see, touch, and handle in the chemistry laboratory is within the macroscopic scale. What is Matter? To describe each of these objects, only a few macroscopic properties are required. However, each of these items can be decomposed into smaller microscopic scale properties. What is Matter? The microscopic scale is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly. What is Matter? Atoms make up everyday objects, consisting of interacting subatomic particles like protons and neutrons. This complexity in characterization requires a large number of variables. What is Matter? Matter vs. Mass Matter vs. Mass Matter should not be confused with mass as the two are not the same in modern physics. Matter vs. Mass Matter is a physical substance of which systems may be composed; while mass is not a substance, but rather a quantitative property of matter and other substances or systems. Matter vs. Mass You might be able to imagine, however, the difficulty for people several hundred years ago to demonstrate that air had mass and volume Matter vs. Mass Air (and all other gases) are invisible to the eye, have very small masses compared to equal volumes of solids and liquids, and are quite easy to compress (change volume). Matter vs. Mass Without sensitive equipment, it would have been difficult to convince people that gases are matter.  Matter vs. Mass Today, we can measure the mass of a small balloon when it is deflated and then blow it up, tie it off, and measure its mass again to detect the additional mass due to the air inside. Matter vs. Mass The mass of air, under room conditions, that occupies a one quart jar is approximately 0.0002 pounds or 0.09 grams.  Matter vs. Mass This small amount of mass would have been difficult to measure in times before balances were designed to accurately measure very small masses. Matter vs. Mass Later, scientists were able to compress gases into such a small volume that the gases turned into liquids, which made it clear that gases are matter. Liquid oxygen Matter vs. Mass The most important method that nature uses to organize atoms into matter is the formation of molecules. What is a molecule? Matter vs. Mass Molecules are groups of two or more atoms that have been bonded together. There are millions of different ways to bond atoms together, which means that there are millions of different possible molecules. Matter vs. Mass Each of these molecules has its own set of chemical properties, and it's these properties with which chemists are most concerned. Matter vs. Mass Each of these molecules has its own set of chemical properties, and it's these properties with which chemists are most concerned. Matter vs. Mass Summary All matter has mass and occupies space. All physical objects are made of matter. Matter vs. Mass Summary Matter itself is composed of tiny building blocks known as "atoms". There are only 118 different types of atoms known to man. Matter vs. Mass Summary Frequently, atoms are bonded together to form "molecules". Physical States of Matter Physical States of Matter Water can take many forms. At low temperatures (below 0°C), it is a solid. When at "normal" temperatures (between 0°C and 100°C), it is a liquid. Physical States of Matter While at temperatures above 100°C, water is a gas (steam). The physical state of the water depends upon the temperature. Each state has its own unique set of physical properties.  Physical States of Matter Matter typically exists in one of three states: solid, liquid, or gas. From left to right: quartz (solid), water (liquid), nitrogen dioxide (gas). Physical States of Matter The state that a given substance exhibits is also a physical property. Some substances, such as oxygen and carbon dioxide, exist as gases at room temperature. Physical States of Matter Others, like water and mercury metal, exist as liquids. Most metals exist as solids at room temperature. All substances can exist in any of these three states. Physical States of Matter A representation of the solid, liquid, and gas states. Physical States of Matter A representation of the solid, liquid, and gas states. (a) Solid O2 has a fixed volume and shape, and the molecules are packed tightly together. Physical States of Matter (b) Liquid O2 conforms to the shape of its container but has a fixed volume; it contains relatively densely packed molecules. Physical States of Matter (c) Gaseous O2 fills its container– regardless of the container’s size or shape – and consists of widely separated molecules. Physical States of Matter A solid has definite volume and shape, a liquid has a definite volume but no definite shape, and a gas has neither a definite volume nor shape. Plasma: A Fourth State of Matter Technically speaking, a fourth state of matter called plasma exists, but it rarely occurs naturally on earth, so we will omit it from our study here. A plasma globe operating in a darkened room Solids Solids  Solids In the solid state, the individual particles of a substance are in fixed positions with respect to each other because there is not enough thermal energy to overcome the intermolecular interactions between the particles.  Solids As a result, solids have a definite shape and volume. Most solids are hard, but some (like waxes) are relatively soft. Many solids composed of ions can also be quite brittle. What are some characteristics of solids?  Solids Solids are defined by the following characteristics: Definite shape (rigid) Definite volume Particles vibrate around fixed axes  Solids Solids are defined by the following characteristics: Definite shape (rigid) Definite volume Particles vibrate around fixed axes  Solids If we were to cool liquid mercury to its freezing point of −39°C under the right pressure conditions, we would notice all of the liquid particles would go into the solid state.  Solids Mercury can be solidified when its temperature is brought to its freezing point. However, when returned to room temperature conditions, mercury does not exist in solid state for long, and returns back to its more common liquid form.  Solids Solids usually have their constituent particles arranged in a regular, three-dimensional array called a crystal. The effect of this regular arrangement of particles is sometimes visible macroscopically, as shown in the image.  Solids Some solids, especially those composed of large molecules, cannot easily organize their particles in such regular crystals and exist as amorphous (literally, “without form”) solids. Glass is one example of an amorphous solid. Liquids  Liquids If the particles of a substance have enough energy to partially overcome intermolecular interactions, then the particles can move about each other while remaining in contact.  Liquids This describes the liquid state. In a liquid, the particles are still in close contact, so liquids have a definite volume.  Liquids However, because the particles can move about each other rather freely, a liquid has no definite shape and takes a shape dictated by its container. What are some characteristics of Liquids?  Liquids Liquids have the following characteristics: No definite shape (takes the shape of its container). Has definite volume. Particles are free to move over each other, but are still attracted to each other.  Liquids A familiar liquid is mercury metal. Mercury is an anomaly. It is the only metal we know of that is liquid at room temperature.  Liquids Mercury also has an ability to stick to itself (surface tension) – a property that all liquids exhibit. Mercury has a relatively high surface tension, which makes it very unique.  Liquids Here you see mercury in its common liquid form. When liquid mercury heated to its boiling point of 357°C under the right pressure conditions, we would notice all particles in the liquid state go into the gas state. Gases  Gases If the particles of a substance have enough energy to completely overcome intermolecular interactions, then the particles can separate from each other and move about randomly in space.  Gases This describes the gas state, which we will consider in more detail elsewhere. Like liquids, gases have no definite shape; but unlike solids and liquids, gases have no definite volume either.  Gases The change from solid to liquid usually does not significantly change the volume of a substance. However, the change from a liquid to a gas significantly increases the volume of a substance, by a factor of 1000 or more. What are some characteristics of Gas?  Gases Gases have the following characteristics: No definite shape (takes the shape of its container) No definite volume Particles move in random motion with little or no attraction to each other Highly compressible  Characteristics of the Three States of Matter Characteristics Solids Liquids Gases shape definite indefinite indefinite volume definite definite indefinite relative intermolecular strong moderate weak interaction strength relative particle in contact and in contact but not not in contact, positions fixed in place fixed random positions What state or states of matter does each statement, describe? 1.This state has a definite volume, but no definite shape. What state or states of matter does each statement, describe? 2. This state has no definite volume. What state or states of matter does each statement, describe? 3. This state allows the individual particles to move about while remaining in contact. What state or states of matter does each statement describe? 4. This state has individual particles in a fixed position with regard to each other. What state or states of matter does each statement describe? 5. This state has individual particles far apart from each other in space. What state or states of matter does each statement describe? 5. This state has a definite shape. Summary Three states of matter exist – solid, liquid, and gas. Solids have a definite shape and volume. Summary Liquids have a definite volume, but take the shape of the container. Gases have no definite shape or volume. Composition of Matter Composition of Matter Composition of Matter Matter can be classified into two broad categories: pure substances and mixtures. Composition of Matter A pure substance is a form of matter with a constant composition (meaning that it is the same everywhere) and constant properties throughout the sample. Composition of Matter (meaning that there is only one set of properties such as melting point, color, boiling point, etc. throughout the matter). Composition of Matter A material composed of two or more substances is a mixture. Composition of Matter Elements and compounds are both examples of pure substances. Composition of Matter A substance that cannot be broken down into chemically simpler components is an element. Aluminum, which is used in soda cans, is an element. Composition of Matter A substance that can be broken down into chemically simpler components (because it has more than one element) is a compound. Composition of Matter Ordinary table salt is called sodium chloride. It is considered a pure substance because it has a uniform and definite composition. Composition of Matter All samples of sodium chloride are chemically identical. Water is also a pure substance. Salt easily dissolves in water, but salt water cannot be classified as a pure substance because its composition can vary. Composition of Matter You may dissolve a small amount of salt or a large amount into a given amount of water. Composition of Matter A mixture is a physical blend of two or more components, each of which retains its own identity and properties in the mixture. Composition of Matter Only the form of the salt is changed when it is dissolved into water. It retains its composition and properties. Composition of Matter Molecule is the general term used to describe any atoms that are connected by chemical bonds. Every combination of atoms is a molecule. A compound is a molecule made of atoms from different elements. All compounds are molecules, but not all molecules are compounds. Composition of Matter A homogeneous mixture, also called a solution, is a mixture in which the composition is uniform throughout the mixture. Composition of Matter The salt water described above is homogeneous because the dissolved salt is evenly distributed throughout the entire salt water sample. Composition of Matter Often it is easy to confuse a homogeneous mixture with a pure substance because they are both uniform. The difference is that the composition of the pure substance is always the same. Composition of Matter The amount of salt in the salt water can vary from one sample to another. All solutions are considered homogeneous because the dissolved material is present in the same amount throughout the solution. Composition of Matter A heterogeneous mixture is a mixture in which the composition is not uniform throughout the mixture. Vegetable soup is a heterogeneous mixture. Composition of Matter Any given spoonful of soup will contain varying amounts of the different vegetables and other components of the soup. Composition of Matter Phase A phase is any part of a sample that has a uniform composition and properties. Composition of Matter By definition, a pure substance or a homogeneous mixture consists of a single phase. A heterogeneous mixture consists of two or more phases. Composition of Matter When oil and water are combined, they do not mix evenly, but instead form two separate layers. Each of the layers is called a phase. Composition of Matter Identify each substance as a compound, an element, a heterogeneous mixture, or a homogeneous mixture (solution). filtered tea freshly squeezed orange juice a compact disc Composition of Matter Tea is a solution of compounds in water, so it is not chemically pure. Because the composition of the solution is uniform throughout, it is a homogeneous mixture. Composition of Matter Orange juice contains particles of solid (pulp) as well as liquid; it is not chemically pure. Because its composition is not uniform throughout, orange juice is a heterogeneous mixture. Composition of Matter A compact disc is a solid material that contains more than one element, with regions of different compositions visible along its edge. Composition of Matter Identify each substance as a compound, an element, a heterogeneous mixture, or a homogeneous mixture (solution). aluminum oxide, a white powder that contains a 2:3 ratio of aluminum and oxygen atoms selenium Composition of Matter Aluminum oxide is a single, chemically pure compound. Selenium is one of the known elements. How would a chemist categorize each example of matter? 1. saltwater 2. soil 3. water 4. oxygen Summary Matter can be classified into two broad categories: pure substances and mixtures. Summary A pure substance is a form of matter that has a constant composition and properties that are constant throughout the sample. Elements and compounds are both examples of pure substances. Summary Elements are the simplest substances made up of only one type of atom. Compounds are substances that are made up of more than one type of atom. Summary Mixtures are physical combinations of two or more elements and/or compounds. Mixtures can be classified as homogeneous or heterogeneous.