Matter and Energy (Malaysian Institute of Aviation Technology) PDF
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Uploaded by HealthfulRutherfordium
UniKL Malaysian Institute of Aviation Technology
2016
Wan Nur Shaqella Bte Wan Abdul Razak
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Summary
This document is a presentation on matter and energy, covering topics such as the nature of matter, chemical compounds, states of matter, and changes between states. It is created for training purposes at UniKL Malaysian Institute of Aviation Technology in February 2016.
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1. MATTER AND ENERGY February 11, 2016 LEARNING OUTCOMES On compleAon of this topic you should be able to: Describe about maJer and energy. 1. Nature of maJer: the chemical elements,...
1. MATTER AND ENERGY February 11, 2016 LEARNING OUTCOMES On compleAon of this topic you should be able to: Describe about maJer and energy. 1. Nature of maJer: the chemical elements, structure of atoms, molecules. 2. Chemical compounds. 3. States: solid, liquid and gaseous. 4. Changes between states. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 2 1.1 NATURE OF MATTER 3 MaJer MaJer is anything that occupies space and has mass Example : wood, water, air Can not be created or destroy, but can change state Example : ice à water à steam Energy released when change state Divided into 2 states of nature MaJer Chemical nature of Physical nature of maJer maJer Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 4 MaJer MaJer -‐ anything that occupies space. -‐ consists of atoms and molecules. Atom -‐ smallest parLcle in an element that has the properLes of the element. Molecules -‐ the combinaLon of two or more atoms. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 5 Atom The smallest chemical element that can exist, made up of: a) Nucleus -‐ center of an atom b) Protons -‐ PosiLve Charged c) Neutrons -‐ No Charged/ Neutral d) Electrons -‐ NegaLve Charged In a balance atom, amount of electron spinning around the nucleus is the same as proton inside the nucleus. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 6 Atom Nucleus -‐ each carrying a posiLve charge are called protons. In addiLon to the protons the nucleus usually contains electrically neutral parLcles called neutrons. Neutrons have the same mass as protons whereas electrons are very much smaller. Neutron -‐ simply adds to the weight of the nucleus. Proton -‐ has mass same as the neutrons. Electron -‐ orbits define the size or volume occupied by the atom. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 7 Atom Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 8 Element An object or substance of only 1 type of atom. Cannot be reduced chemically into smaller substance. Currently there are 109 elements known. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 9 Molecule The smallest parLcle of a substance that sLll remain the same substance. A chemical combinaLon of 2 atoms. These molecules are packed Lghtly together so that substances appear as solids, liquids or gasses. Forces of a[racLon and repulsion exist between all molecules and these forces which are electro-‐magneLc, vary with the state in which the substances exist. E.g. A molecule of H2O. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 10 Molecule Atoms bond together to form a molecule. Molecules Monatomic Molecule Chemical Compounds Consists of single type of Made up of two or atom. more atoms. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 11 Structure of Atoms Electrons are arranged in energy levels and shells around the nucleus and with increasing distance from the nucleus . Valence electrons : -‐ How many electrons an atom has in its outer shell. -‐ Determines the chemical behavior. -‐ The more valence electrons, the more want for the atom to get more electrons. Valency : 1. bonding capacity of an atom; usually equals the number of unpaired electrons in the atoms outermost shell. 2. No. of bonds it can make with a monovalent atom such as Hydrogen. q Monovalent q Bivalent q Trivalent q Tetravalent Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 12 Atomic Structure 1. An atom consists largely of empty space. 2. At its centre is the nucleus, which is formed from closely packed protons and neutrons. 3. Surrounding this is a ‘cloud’ of orbiLng electrons circulaLng around it in all direcLons. 4. Protons are posiLvely charged parLcles and electrons are negaLvely charged parLcles. 5. There must be as many electrons orbiLng the nucleus as there are protons within the nucleus. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 13 Atomic Structure 6. Where the molecules of a substance consists of only one type of atom, the substance is classified as an element. 7. All atoms of a parLcular element contains a definite number of protons and subsequent electrons. 8. It is the number of protons in an atom that provide the ATOMIC NUMBER, and the total mass of all the sub-‐atomic parLcles (protons, neutrons and electrons) that provide a measure of the ATOMIC WEIGHT. 9. Element that have the same number of protons in the nucleus but different relaLve atomic masses as a result of different number of neutrons are called ISOTOPES. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 14 Atomic Structure Atomic Number – no. of protons in the atom’s nucleus. eg. Hydrogen has 1 proton – atomic no. is 1. Carbon has 6 protons – atomic no. is 6. Mass Number – total no. of protons and neutrons in nucleus. eg. Lithium has 3 protons & 4 neutrons – mass no. 7. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 15 Atomic Structure ISOTOPES are atoms that have same atomic number but different mass numbers. Atom gains / loses one or more neutrons from nucleus will become ISOTOPES. Are present in most elements and may also be man made. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 16 Atomic Structure 10. Normally atoms are electrically neutral, as far as charge is concerned, because electrons and protons are present in equal numbers. 11. An atom can become posiLvely or negaLvely charged if it has electrons taken away or added. 12. An ion is therefore an atom which has lost or gained an electron. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 17 Ions q ElectronegaAvity – tendency of atom to a[racts electrons to itself. q ElectroposiAvity – tendency to lose its electrons. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 18 Atomic Structure 13. Metals represent a category of elements endowed with parLcular properLes. 14. One of these is that some of the electrons in the outer shells are so loosely Led to the nucleus that they are effecLvely free and move easily from one atom to another. 15. Applying an external electrical force (such as that provided by a ba[ery or generator) they can all be made to move in the same direcLon. 16. When all the electrons move in one direcLon the current is known as Direct Current (DC), as when a ba[ery is used to provide the electrical force (voltage). Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 19 Atomic Structure 17. When the electrons are moved forwards and backwards, then the current is called alternaLng current (AC). 18. AC current on aircrag usually has a frequency of 400Hz. 19. This orderly movement of electrons is called current. Metals which easily permit the orderly movement of electrons are called Conductors e.g. copper, aluminium, silver, plaLnum, bronze and gold. 20. In other materials the electrons are held more firmly in their outer shells. In these material it is almost impossible to induce an orderly movement of electrons. They are classified as Non-‐Conductors or Insulators. E.g. glass, rubber, plasLc, wood, etc. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 20 ATOM Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 21 Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 22 The family of elements called semiconductors someLmes behave like conductors and someLmes like insulators. Typical material are silicon and germanium. These materials have four valence electrons, each atom shares its electrons with adjacent atoms to form a strongly bonded structure called a crystal lahce. However electron movement can be achieved by heaLng as the temperature rises the electrons become more agitated and leave their orbits. This is known as “intrinsic” conducLon. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 23 ELECTRONS Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 24 Chemical ReacAons Chemical reacLons are concerned with the loss or gain of electrons in the outer shells. Elements with deficiencies in their outer shells are chemically very acLve and form compound easily. Chemical reacLons, and some physical phenomena such as the conducAon of electricity and the emission of light in LEDs, involve electrons in the outer shells of atoms. A COMPOUND is defined as the chemical combinaLon of two or more elements and by chemical means can be separated back into their original elements. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 25 Chemical ReacAons Metallic compound -‐ metal + metal (eg: Alloy) Ionic compound -‐ metal + non-‐metal (eg: sodium chloride) In an ionic compound, electrons move from the outer shell of one atom Lthe outer shell of another. This leaves charged parLcles called ions. Ionic compounds include acids, salts and alkalis. Covalent compound -‐ non metal + non metal (eg : water) The bonds are formed when atoms share electrons. These electrons are from the outer shell of an atom. Covalent compounds include water, methane, sugar, plasLcs and rubber. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 26 Chemical ReacAons Chemical reacAons are concerned with the loss or gain of electrons in the outer shells. Elements with deficiencies in their outer shells are chemically very acLve and form compound easily. Example: Sodium (Na) with and atomic number of 11 and Chlorine (Cl) with and atomic number of 17. Na Cl Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 27 1.2 CHEMICAL COMPOUND 28 Chemical Compound Defined as: ‘A substance made up of different elements that are chemically bonded and are so united that the whole has proper7es of its own, which are unlike those of its cons7tuents.’ All other molecules made up of two or more atoms are known as Chemical Compound. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 29 1.3 STATES 30 Solid A rigid form, has a definite volume and shape (independent of its container) Low energy state Incompressible Heat added to solid, molecular movement cannot move far / close together Solid molecule are closely pack together. Permitting low movement activities in the molecules Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 31 MOLECULES IN SOLID Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 32 Liquid Assume the shape of the container but does not fill Higher energy state ParAally bond together, the bonding force is called surface tension Molecules are loosely packed in a liquid Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 33 MOLECULES IN LIQUID Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 34 Gas Consume the shape of the container H e a t e n e r g y a d d e d – m o l e c u l a r movement increase further All surface tension can no longer hold the molecules à molecules escape as gas Lighter than air & will expand to fill the container Very high energy state Compressible Boiling point is varies directly with pressure E.g. water boils less than 100 oC when pressure is lower than atmospheric Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 35 Example Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 36 1.4 CHANGE BETWEEN STATES 37 Explain the phase transformation of matter from a solid state to gas? Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 38 Enthalpy changes during the change of state – Ice to Steam Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 39 Changes between states Solid to Liquid – Fusion (MelAng) i. When a solid is heated, the molecular movement is speeded up unLl it becomes great enough to overcome the cohesive force that held the solid in its rigid shape. The volume of the liquid does not differ greatly to that of the solid. ii. The temperature at which this occurs is called the MelLng Point. Liquid to Gas – VaporisaAon (Boiling) i. When a liquid is heated, the speed of the molecules again is speeded up unLl it becomes great enough to break the intermolecular bonds and a gas is formed. There is a large change in volume when this occurs (the volume of a gas is approximately 1000 Lmes that of the liquid). ii. The temperature at which a liquid boils (changes from liquid into a gas) is determined by the pressure that is above the liquid. The greater the pressure, the ho[er the liquid will have to be before it boils. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 40 Changes between states Gas to Liquid – CondensaAon i. When heat is removed from a gas, its temperature drops unLl it reaches the temperature at which is boiled. As more heat is removed, the vapor returns to the liquid phase. ii. In condensing, vapor gives up an amount of heat equivalent to the heat required to vaporize it. The difference is only in the direcLon of heat transfer. Heat energy expelled is called the Latent Heat of CondensaLon. Liquid to Solid – SolidificaAon or Freezing i. When heat is removed from a liquid, its temperature will drop unLl it reaches its melLng temperature. As more heat is removed, the liquid returns to its solid phase. This process is called freezing, or solidificaLon. ii. The heat of solidificaLon is exactly equal to the heat of fusion. Thus the only disLncLon between freezing and melLng lies in whether heat is being released or absorbed. Loss of molecular energy is the Latent Heat of SolidificaLon. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 41 Solid to Gas – SublimaAon i. Some solid substance when heated do not melt, but form a Vapour. ii. Solid to vapour, without passing through liquid state. iii. Eg. dry ice – solid carbon dioxide is known as “dry ice” and sublimates at room temperature. iv. Eg. freeze-‐drying – water can be sublimated in a food product by using a vacuum. Gas to Solid – DeposiAon i. The process of changing state from gas to solid. ii. Water vapor to ice – water transforms directly into ice without becoming a liquid, a process that ogen occurs on windows during the winter months. Prepared By: Wan Nur Shaqella Bte Wan Abdul Razak 42
