Copy of B-2.1 - Matter 1.pptx

Module: B-2 - Physics Topic 2.1: Matter  INTRODUCTION On completion of this topic you should be able to: 2.1.1 Define the nature of matter regarding: The chemical elements Structure of atoms...

Module: B-2 - Physics Topic 2.1: Matter  INTRODUCTION On completion of this topic you should be able to: 2.1.1 Define the nature of matter regarding: The chemical elements Structure of atoms Molecules 2.1.2 Define chemical compounds. 2.1.3 Define matter in solid, liquid, and gaseous states. 2.1.4 Identify changes between states of matter and define the process. 30-03-2024 Slide No. 2  MATTER Matter is a very general term that is used to describe all kinds of substances. To understand aircraft materials, processes, and systems – You must understand the different properties of matter. Matter refers to everything which occupies space and has mass. The volume of any substance is the amount of space it occupies. 30-03-2024 Slide No. 3 30-03-2024 Slide No. 4 30-03-2024 Slide No. 5  MATTER Mass cannot be created or destroyed. Burn 1kg – still have 1kg of ash, smoke, and gas. Density is defined as Mass per unit Volume – (m/V). Solids and Liquids are incompressible – Fixed density. Gases are compressible. 30-03-2024 Slide No. 6  ATOMIC STRUCTURE MODELS Almost all an atom’s mass is concentrated in nucleus – protons and neutrons ≈ 1850 times mass of electrons. Number of protons and neutrons differ between different types of atoms – size and mass of different atoms vary a great deal. Atoms are the smallest constituent of ELEMENTS – Matter in its simplest form. 30-03-2024 Slide No. 7  ATOMIC STRUCTURE Within the atom, there are four Fundamental Interactions which give rise to all other physical processes in the Universe. In order of increasing strength, they are: 1. Gravity, very insignificant on the atomic scale. 2. The Weak Nuclear Interaction, which contributes to radio activity. 3. Electromagnetic Interaction, source of electrical and magnetic energy. 4. The Strong Nuclear Interaction. Holds the nuclei together. Proton - positive electric charge Electron, a negative electric charge 30-03-2024 Slide No. 8  ATOMIC STRUCTURE An element is matter in which all the atoms or molecules are identical. Elements are detailed in the Periodic Table. For example, pure Copper is an element because it is comprised of Copper atoms (Cu). An element retains its properties as an atom. 30-03-2024 Slide No. 9  ATOMIC STRUCTURE Electrons surround the nucleus in successive groups or shells – like spheres within spheres. Copper atom has 28 electrons in three shells and one electron in outer fourth shell. Whether the outer shell is relatively empty, half full, or nearly full determines some of the electrical properties of the element. 30-03-2024 Slide No. 10  CHEMICAL ELEMENTS AND THE ATOMIC PERIODIC TABLE 30-03-2024 Slide No. 11  ATOMIC NUMBER COPPER The Periodic Table arranges all the known elements in order according to atomic number. The number of protons in an atom determines what element it is. The number of protons always equals the number of electrons in an atom, and that number is equal to the atomic number. 30-03-2024 Slide No. 12  THE PERIODIC TABLE 82 – Atomic Number - corresponds to the number of protons in the atom. Pb – Symbol for the element ‘lead’ (an abbreviation of the Latin ‘plumbum’). 207 – Atomic Mass - average mass of the element expressed in atomic mass units (amu). The mass of an atom refers to the mass of protons and neutrons (electron mass is insignificant) 1 amu = 1.66 x 10-27 kg. 30-03-2024 Slide No. 13  IONS Normal atoms have a neutral charge, that is, there is the same number of positively-charged protons as there are negatively-charged electrons. An ion is an atom that has lost or gained electrons. The charge will be positive if the atom has lost electrons and negative if the atom has gained electrons. 30-03-2024 Slide No. 14  ISOTOPES Isotopes are atoms of the same element with different numbers of neutrons. The Atomic Number remains the same, but the Atomic Mass changes. Not all isotopes are radioactive. 30-03-2024 Slide No. 15  MOLECULES and COMPOUNDS Atoms can chemically combine with other atoms to form molecules. Matter comprised of different elements are called compounds. 30-03-2024 Slide No. 16  COMPOUNDS A compound is matter in which all the molecules are identical, but the molecules are comprised of different atoms in exact proportions. The two or more individual elements are chemically combined to form a separate substance whose characteristics may be completely different from the original element characteristics. 30-03-2024 Slide No. 17  MOLECULES Water is a compound because it is made up of Hydrogen and Oxygen atoms (H2O). The same is true of Carbon Dioxide (CO2) and Common Salt, Sodium Chloride (NaCl). 30-03-2024 Slide No. 18  MOLECULES Molecule – smallest particle of any element or compound which can have a separate existence and still retain the distinctive property of that element or compound. A molecule can have: Just one atom (Helium) Two atoms of the same element (Oxygen – O2) Atoms of several different elements (Water – H2O) 30-03-2024 Slide No. 19  MOLECULES Bonding is achieved by transfer of, or sharing of, the electrons in the outer shell. Subscripts indicate number of particular atoms in the molecule – Al2 O3 means two atoms of Aluminum and three atoms of Oxygen in each molecule of Alumina. 30-03-2024 Slide No. 20  MIXTURES A mixture is a mingled mass of two or more substances where each substance retains it own individual characteristics. This image is a representation of NaCl in H2O – salty water. NaCl – Sodium Chloride H2O – Water. Mixtures have varying ratios of elements that do not combine chemically as they do in a compound. Examples of mixtures are Salty water Air – 21% Oxygen, 78% Nitrogen, 1% Carbon Dioxide and other gases Metal alloys – Brass (Copper and Zinc), Steel (Iron and Carbon) 30-03-2024 Slide No. 21  MIXTURES Metal alloys sometimes change characteristics when the metals are merged. For example, Aluminum becomes stronger and harder when alloyed with certain other metals. This is a physical rather than a chemical combination. This picture is a microscopic cross- section of a metal alloy showing crystalline structure. Mixtures may be separated into the original substances. 30-03-2024 Slide No. 22  MOLECULES and MATTER Molecules of any substance are not stationary. They vibrate around rapidly and continuously. What we call ‘temperature’ is, in fact, only a measure of this molecular activity. Speed at which molecules move about, and the distance they travel, are different in solids, liquids, and gases, and are greater when a substance is hot than when it is cold. 30-03-2024 Slide No. 23  STATES OF MATTER Matter can exist in three states – solid, liquid or gas. Solids have a definite shape and volume Liquids have a definite volume but no regular shape, they take the shape of their container Gases have no fixed shape or volume. Like liquids they take the shape of their containers but, unlike liquids, their volume is readily altered by expansion or compression It is possible to change the state of most substances by changing their molecular activity. For example, Liquid Mercury can freeze, Solid Lead can melt, Gaseous Oxygen can liquefy. 30-03-2024 Slide No. 24  MOLECULES and MATTER The physical condition of a compound has no affect on a compound’s chemical structure. In other words, ice, water, and steam are all H2O, and the same type of matter appears in all of these states. Molecules of any substance exert a force of attraction upon each other – molecules in solids bound closely together – allow less freedom to move compared to liquids or gases. Gases flow more easily than liquids because their molecules have weak attractive forces and high levels of motion energy. 30-03-2024 Slide No. 25  SOLIDS, LIQUIDS AND GASES As more heat is applied, the molecules or atoms move so freely that they break the bonds of their solidity but still retain attraction to each other. It is said the substance has melted and the state it has reached is a liquid. 30-03-2024 Slide No. 26  SOLIDS, LIQUIDS AND GASES If more heat is applied to a liquid, the molecules or atoms gain so much energy that they are capable of breaking their attractive bonds to each other and can break free of the liquid mass. This phenomenon is termed vaporisation and the liquid is now in a gaseous state. This process is also called ‘boiling’. At standard sea level pressure of 1013 millibars, water boils at 100° C. At an altitude of 18 000 feet where the atmospheric pressure is about 500 millibars, water boils at about 80° C. 30-03-2024 Slide No. 27  MATTER The density of a substance is its mass per unit volume. Density of a substance determined by mass of the atoms which comprise its molecules, and by how closely the molecules are packed. 30-03-2024 Slide No. 28  MATTER Solids are usually more dense than liquids – plenty of exceptions: Cork, Balsa. Gases are the least dense of the three states of matter. Density expressed in any units of mass per any units of volume, eg: Grams per cubic centimetre (g/cm3) Grams per litre (g/l) Pounds per cubic foot (lb/ft3) Pounds per gallon (lb/gal) 30-03-2024 Slide No. 29  SOLIDS, LIQUIDS AND GASES If an element normally exists as a solid (e.g. most metals at room temperature), the easiest way to change its state is to increase or decrease its temperature. The molecules or atoms in a solid vibrate but cannot move as freely as the other states. As the temperature of the substance is raised, the molecules or atoms gain energy and start to move more freely. This allows the solid to expand initially. 30-03-2024 Slide No. 30  VOLUME It is harder to change the volume of most solids than it is to change the volume of liquids or gases. Liquids, and especially gases, expand or contract more readily with change of temperature than solids do. Gases expand and contract more readily with pressure change than liquids or solids. 30-03-2024 Slide No. 31  CONCLUSION Now that you have completed this topic, you should be able to: 2.1.1 Define the nature of matter regarding: The chemical elements Structure of atoms Molecules 2.1.2 Define chemical compounds. 2.1.3 Define matter in solid, liquid, and gaseous states. 2.1.4 Identify changes between states of matter and define the process. 30-03-2024 Slide No. 32  This concludes: Module: B-2 - Physics Topic 2.1: Matter