Atoms and Elements Class Notes and Class Work

Transcription

1 Atoms and Elements Class Notes and Class Work Introduction to Matter Property: Characteristics matter has. Law: A rule nature seems to follow. It s been observed regularly. Theory: Tries to explain the law The Particle Theory of Matter 1. Matter is made up of particles (Atoms, molecules, and ions) 2. Pure substances: One kind of matter or particles ex. H 2 O (Water) Impure substances: Two or more kinds of matter or particles. ex. Sugar + Water 3. All particles have an attraction to each other 4. Particles are in constant motion 5. Particles are not moving at the same speed Class Work 1. What is a definition of matter and of property? 2. List three properties of matter to explain each of the following: 3. Use the particle theory of matter to explain each of the following: a) Gases have low density (mass/volume) b) Some substances are solids at room temperature. c) Some substances have high boiling points. d) Some substances are the same throughout. e) An impure substance like sand and salt is not the same throughout 4. What is the difference between the law of gravity and the theory of gravity? Lesson 2 - Physical and Chemical Properties Physical Property: A characteristic that can be determined without changing a substance into a new substance. Quantitative Observation: involves measurement. Qualitative Observation: Not involving measurement or numbers. Chemical Properties: A characteristics that can only be determined when a substance is changed into a new substance. Class Work: Read pages 159 to 194 Text Questions: Page 188 (4,5,6,8 and 9) Page 289 (15,18,22,40)

2 Lesson 3 Physical and Chemical Changes Physical Change: a change in a substance with new properties being produces (without a new substance). A physical change does not produce a new substance. Chemical Change: an alteration in a substance in a substance in which a new substance(s) is produced., having new physical and chemical properties. (also know as a chemical reaction) Evidence that a chemical change may be taking place: 1. There is a change in temperature because heat energy is either being given off or absorbed. 2. There is a permanent change in colour. 3. There is a formation of new odour. 4. Bubbles of gas are produced in the liquid after two liquid solutions are mixed. 5. A solid starting material gets used up. 6. A new substance with new properties appears to form. Class Work: Text Reading: p ; 169 Text Questions: p. 188 # 10 & 11 p. 290 # 23 a., b., & c. 1. Which one of the following is a physical change and which is a chemical change? a) The burning of rubber b) The rotting of an apple c) The melting of sodium chloride d) The stretching of rubber e) The crushing of a rock f) The rusting of a machine g) The burning of a match h) The condensation of a gas to a liquid i) The formation of hydrogen gas when hydrochloric acid is mixed with magnesium 2. State what evidence, if any, there is that a chemical change is taking place in each of the following: a) A gas condenses to form a liquid and heat energy is released. b) When sodium hydroxide solution is added to hydrochloric acid solution heat energy is released and sodium chloride and water are formed. c) When an Alka-Seltzer is added to water there is much fizzing as carbon dioxide gas is produced. d) When sugar is added to water and the liquid stirred, the sugar disappears.

3 Name: Date: Lesson 4 Classification of matter Matter Homogeneous Matter Heterogeneou s Matter Pure Substances Element Solution Compound Ordinary Mechanical Mixtures Mechanical Mixtures Suspension Colloid

4 Name: Date: Use arrows to match the words with definitions then place words in the flow chart above: Matter A heterogeneous mixture. Homogeneous matter Heterogeneous matter Pure substance Impure substance A pure substance that is made up of two or more elements joined by chemical bonds Anything that has mass and occupies space. A mechanical mixture whose parts are smaller than an ordinary mechanical mixture. Matter that contains only one kind of matter and one kind of particle. Mixture Solution Mechanical Mixture Suspension Colloid Ordinary Mechanical Mixture Element Compound A mechanical mixture whose suspended particles are too small to be separated by gravity. Matter that is uniform or constant or the same throughout. Matter that contains more than one kind of matter and more than one kind of particle. Matter that is not the same throughout. Matter that is composed of two or more elements or compounds or combinations of elements and compounds. Contains Large parts observable with the naked eye. A pure substance that cannot be broken down into other substances by ordinary chemical means. A homogeneous mixture.

5 Lesson 5- Discovery of Elements, their Symbols, and the Abundance of elements Elements have been known since ancient times. By 1669 there were 14 elements known. By 1860 there were approximately 60 known elements. Today there are approximately 115 known elements. Jakob Berzalius, A Swedish chemist devised the symbols for elements in Usually single capitol letter or two letters with the second being a smaller letter. Ex. Boron-B Hydrogen-H If two or more elements begin with the same letter you use two letters. Ex. Hydrogen-H Helium-He Sometimes the first letter rule does not seem to be followed because it is based on the Latin word. Ex. Gold(Aurium)-Au Potassium(Kalium)-K The symbols for elements are universal. Some elements are named after famous scientist: Einstenium Curium Nobelium Some elements are named after countries or states. Polonium Francium Germanium Californium Lastly, some elements have been named after a special property they have or after names in Greek mythology. Helium-Helius The Abundance of elements In our atmosphere (Dry air) Nitrogen-N % Oxygen-O % Argon-AR 0.94% Other trace amounts of: Xenon, Krypton, Helium, Neon and Compound CO2

6 The percentage composition of the most abundant elements in the earth s crust and atmosphere is: Oxygen O 49.20% Silicon Si 25.67% Aluminum Al 7.50% Iron Fe 4.71% Calcium Ca 3.39% Sodium Na 2.63% Potassium K 2.40% Magnesium Mg 1.93% Hydrogen H 0.87% Titanium Ti 0.58% Chlorine Cl 0.19% Phosphorous P 0.11% Manganese Mn 0.09% Carbon C 0.08% Class Work The most abundant element in the Universe is Hydrogen(H) Text reading: p. 190, 192, Text questions: p. 189 (#16) p. 197 (# 1 a & b, 4, 5) p. 214 (# 1, 2, 3) p. 224 (#1, 6, 8)

7 Lesson 6- Model of the Atom Atom: An atom is the defining structure of an element, which cannot be broken by any chemical means. A typical atom consists of a nucleus with protons and neutrons, and electrons circling this nucleus. Nucleus: Is made up of neutrons (electronically neutral) and protons (positive charge), collectively called nucleons. Electrons: negatively charged subatomic particles Sub-atomic particle Charge Proton +1 Neutron 0 Electron 1 Since, under normal conditions, the atom as a whole is electrically neutral, the number of electrons must equal the number of protons in the nucleus. Neils Bohr model of the Atom: He compared the atom to the solar system: Nucleus is like the sun Electrons are like the planets circulating the sun. Electron Shells: The fixed path or orbits in which the electrons travel around the nucleus. Example of the Bohr-Rutherford model: The lowest energy level (first or innermost shell) can hold 2 electrons, the second energy level (shell) can hold 8 electrons and the third energy level (shell) holds 8 electrons (with 10 in reserve).

8 Modern Models: The most modern model of the atom is called the Quantum mechanical model or Wave mechanical model and was developed around It is more complex than the Bohr-Rutherford model and is covered in High School. Class Work: 1) In the Bohr model, what does the term orbit or electron shell mean? 2) Draw electron shell diagrams for: a) O- 2 electrons in the first shell, 6 in the 2 nd. b) P- 2 electrons in the 1 st shell, 8 in the 2 nd, 5 in the 3 rd. c) Ge- 2 electrons in the 1 st shell, 8 in the 2 nd, 18 in the 3 rd, 4 in the 4 th. 3) Textbook questions: p.244 1, 3 p.254 3,4,8,9, 22, 23 p , 19, 29, 38 Lesson 7-Atomic Mass and The Periodic Table Atomic Number: is the number of protons (which equals the number of electrons) in each atom of the element. For example, any atom that contains exactly 47 protons in its nucleus is an atom of silver. Relative atomic Mass Atomic Mass: the number of protons + the number of neutrons in an atom. In the case of silver it would be 108 (47 Protons and 61 neutrons) All the atoms of any particular element must have the same number of protons(and therefore electrons). Hydrogen (with an atomic number of 1) for example has one proton. But there is no reason why the number of neutrons can't vary. Isotopes: are atoms of the same element that have different masses. Meaning they have a different number of neutrons. In fact, there are three types of hydrogen atom, each containing a different number of neutrons. We call these isotopes of hydrogen. Look at the diagram below to see the isotopes of hydrogen. The two heavier isotopes of hydrogen are often known as deuterium ( ) and tritium ( ).

9 Different isotopes of an element have the same atomic number (1), but different atomic mass numbers. Different isotopes of an element have different mass numbers, but react chemically in exactly the same way. Relative Atomic Mass: of an element is the average mass of the isotopes in a naturally occurring sample of the element, taking into account the proportion of each isotope present. The Modern Periodic Table (p. 562 in your text) Modern Periodic Law: States that when elements are arranged in order of increasing atomic number, elements with similar properties occur at regular intervals. (Sometimes every 8 or 18 etc.) i.e. Elements with similar properties occur periodically. The State of Elements: Most elements are solid at room temperature A few elements are liquids such as Bromine and Mercury A small number are gases such as hydrogen, nitrogen, oxygen, fluorine, chlorine, and group 18 noble gases (see below) Classification of Elements: Elements can be classified as metals, non-metals or metalloids. Classification Metals Non-Metals Metalloids have lustre The opposite of Some properties of good conductors of metals Metals and some heat and electricity properties of nonmetals. malleable(can be hammered) ductile (can be drawn into wire) Physical properties Chief chemical properties Lose or give up electrons easily Gain or accept electrons easily

10 Where are metals, non-metals and metalloids found in the periodic table? The Periodic table has: elements placed Horizontally (rows or periods) elements placed vertically (columns or group) Elements in the same column or group have similar properties and are called a Family. Group 1: Alkali metal family- React with water to produce hydrogen gas and other products Group 2: Alkaline earth metal family- Group 17: Halogen family Group 18: Nobel gas family As you go down groups 1 and 2 the metals are more reactive.