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Chemistry Unit: The particle theory of matter States of matter Classification of matter Heterogeneous and homogeneous Chemical and physical properties Physical and chemical changes Dalton’s atomic theory Elements Atoms, molecules, and diatomic molecules Mendeleev’s periodic table – groups/columns and periods/rows Metals, non-metals, metalloids and noble gases Atomic number, symbols and atomic mass Subatomic particles – protons, neutrons and electrons Bohr – Rutherford diagrams Lewis Dot Diagrams Isotopes Space Exploration Unit: Celestial bodies (types and motion) Ancient Civilizations Geocentric and heliocentric models The sun Inner and outer planets Order of the planets in the solar system Scale and planet models Astronomical units Asteroids, comets and meteors Evolution of the stars Big Bang Theory Exam Practice Questions: Chemistry: 1. Describe the four points of the particle theory of matter. All matter is made up of tiny particles. One substance is made up of all the same particles and different substances are made of different particles. Particles are always moving; the more energy the particles have, the faster they move. There are attractive forces between two particles. These forces are stronger when the particles are closer together. 2. Draw an ice cube in its solid, liquid and gaseous states, using the particle theory. 3. Describe the difference between a chemical and a physical property. Give an example of each. A physical property is a characteristic or description of a substance that may help to identify it. (colour, texture, odor, lustre, clarity, or taste) A chemical property describes the behaviour of a substance as it becomes a new substance. 4. Describe what happens during a chemical change and a physical change. • Physical Change: No new Substance is formed, the process can be reversed. Example: Example: Ice melting into liquid water. • Chemical Change: At least one new substance is produced. Cannot, or is very difficult to, reverse. Example: Burning paper. 5. How can you tell the difference between a chemical and a physical change? A physical change is a change of state, change can be reversed A chemical change has occurred when : o A new colour appears, Heat or light is given off, Bubbles of gas are formed, A solid material (or precipitate) forms in a liquid, The change is difficult to reverse 6. Describe if a physical or chemical change is taking place in the following: a) Mixing salt and pepper; why? Physical: No new substance has been produced, can separate particles b) Baking a cake; why? Chemical: New substance, cannot reverse the process c) Rust forming on metal; why? Chemical: New substance, cannot reverse the process d) Chocolate melting; why? Physical: No new substance has been formed, reversible 7. Describe the difference between a compound and a molecule. • Compounds are pure substances that are made up of two or more different elements • Molecule: Composed of 2 or more elements that are joined by chemical bonds. 8. What is an atom? Atom: All matter is made up of atoms. Atoms are the smallest unit of an element that maintains the properties of that element 9. Describe the 4 points of Dalton’s atomic theory. 1. All matter is made up of small particles called atoms. 2. Atoms cannot be created, destroyed, or divided into smaller particles. 3. All atoms of the same element are identical in mass and size, but are different in mass and size from other elements. 4. 4. Compounds are created when atoms of different elements link together in definite proportions. 10. Who created the periodic table? Dmitri Mendeleev 11. Explain how elements on the periodic table are arranged and describe the importance of developing symbols for each of the elements. • He organized each of the elements according to their atomic masses. As new elements were discovered they fit into Mendeleev’s basic framework for the periodic table. • Previous to the periodic table there was no organization. Creating symbols allowed universal recognition of the elements, regardless of language barriers. 12. Explain the difference between groups and periods on the periodic table. Groups: Elements have similar physical and chemical properties. They are the vertical columns. Periods: Horizontal rows have similar properties and gradual changes in these properties. 13. What are some characteristics of Alkali Metals? Alkaline Earth Metals? Halogens? Nobel Gases? Alkali: These elements are all shiny, silvery metals that are extremely reactive. Alkaline Earth Metals: Shiny, silvery-white colour, highly reactive but not as reactive as the Alkali metals Halogens: The halogens are the most reactive non-metals Nobel Gases: These gases are un-reactive and almost never form compounds with other elements. 14. Describe the difference between metals, non-metals and metalloids. Metals: Metals are shiny solids are room temperature, with characteristic high melting points and densities. Electrons in the valence shell of metal atoms can be removed easily. Metals have the ability to be deformed without breaking. They are found on the left side of the table. Good conductors (able to transfer electricity and heat), Malleable (Can be moulded into different shapes) Non-metals: They are generally poor conductors of heat and electricity. Solid nonmetals are generally brittle, with little or no metallic luster. Most nonmetals have the ability to gain electrons easily. They are found on the right side of the table (except hydrogen). Often have a dull surface lustre if they are a solid. Not malleable or ductile – usually brittle Metalloids: Elements that have both metallic and nonmetallic properties are called metalloids 15. Draw and label the structure of an atom. Describe the subatomic particles. 16. Calculate the following: Element Mg K Be F Atomic # 12 19 4 9 Atomic Mass 24 39 9 19 # Protons # Electrons # Neutrons 12 12 12 19 19 20 4 4 5 9 9 10 17. Write the symbol for nitrogen using the proper notation. 147N 18. Use the periodic table to complete the following: Name of Substance Chemical Formula Compound or Element? Elements present How many atoms of each element? helium gas He Element Helium 1 Iron, Sulphur, Oxygen, Hydrogen Sulphur Oxygen Magnesium Phosphorous Oxygen 1 1 9 10 1 3 15 10 40 iron (II) sulfate FeS04 - 5H2O C sulfur trioxide SO3 C Magnesium phosphate 5Mg3(PO4)2 C 19. What is an ion? Atoms that have lost or gained electrons 20. Describe the difference between a cation and an anion. Cation: atoms that have lost an electron and have a positive charge Anion: atoms that have gained an electron and have a negative charge 21. Describe Neils Bohr’s contribution to science. Neils Bohr (1885 – 1962), explained why in the atom electrons do not spiral into the nucleus. Bohr’s model equated the nucleus of an atom to the sun, and the electrons to the planets. The atoms positive nucleus exerts a strong force of attraction on the negative electrons. 22. Explain in full all parts of the Bohr diagram. Describe each structure and state how the Bohr diagram relates to the periodic table. A Bohr diagram includes the protons and the neutrons located inside of the nucleus. The electrons travel in energy shells around the outside of the nucleus. Protons have a positive charge, neutrons are neutral, electrons have a negative charge. The number of protons is the same as the atomic number of the element and the protons plus the neutrons equal the atomic mass. The number of energy shells corresponds to the period of the element. The first energy shell can hold 2 electrons, the second can hold 8 and the third can hold 8. The valence electrons for each Bohr diagram correspond to the group of the element, and determines how an element reacts with other elements. 23. What is the outer shell called? What are the electrons in the outer shell called? Valence shells, valence electrons 24. Draw a Bohr diagram and a Lewis dot diagram for: Li, Mg and S. 25. What is an isotope? • Atoms of the same element can have different number of neutrons; these are called isotopes. Symbol Isotope Name Atomic Mass # Protons # Neutrons F N-15 C-14 K 19 15 14 39 9 7 6 19 Fluorine Nitrogen - 15 Carbon - 14 Potassium 10 8 8 20 Most Common? Y/N Y N N Y Space: 1. What is a Celestial body? Celestial bodies is the term used to describe the Sun, Moon and stars 2. Explain the importance of the sky to people from ancient civilizations. What did they use the sky for? – People watched the sky to tell: the time of day, the date, the weather, their position on Earth, when the tides would be higher or lower than usual. 3. Describe the main idea of the Geocentric model. • Early scientists believed that the Earth was at the center of a giant sphere on which the sun, moon and planets were attached. 4. Describe the main idea of the Heliocentric model. • This model placed the Sun at the center with the Earth and other planets travelling westward around it. 5. Explain how the two models are different and what led to the change in perspective. 6. Describe the composition of the sun. • The sun is a huge globe composed of mostly hydrogen and helium. 7. What occurs during a solar eclipse? The moon is in between the Earth and the sun blocking out the light from the sun. 8. How are the planets in our solar system arranged? Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. 9. List the inner planets and the outer planets. Inner: Mercury, Venus, Earth, Mars, Outer: Jupiter, Saturn, Uranus, and Neptune. 10. Describe the differences between the inner and outer planets. Inner planets are closer to the sun and are terrestrial (made of rock), the outer planets are farther away from the sun and are gaseous. 11. How we compare the distance of planets from the sun and size of planets to Earth. Explain why we do this. We compare distance and size in relation to Earth using Earth diameters and Astronomical Units. We use the Earth as a reference point because it is where we are located and the planet we know the most about. 12. Explain why Pluto is no longer considered to be a planet. • A planet must meet the following 3 requirements in order to qualify as a planet: It needs to be in orbit around the Sun, it needs to have enough gravity to pull itself into a spherical shape, and it needs to have “cleared the neighbourhood” of its orbit. Due to the small size of Pluto it does not meet the third criteria. 13. Describe the difference between an asteroid, comet and a meteor. • • • Asteroids: Rocks floating in space. These can range in size from 1m to hundreds of km. Comets are made up of ice and dust and orbit the sun at large distances. Rock fragments that burn up on entry into Earth’s atmosphere, producing enough light to be seen are meteors. 14. Explain why in Nova Scotia we have 4 distinct seasons. Nova Scotia has distinct seasons due to where we are located in relation to the equator. We are north of the equator so we do not get direct sunlight all of the time. During our summer months we are tilted towards the sun so we receive more direct sunlight. During our winter months we are tilted away from the sun so we receive less direct sunlight. Our fall and spring seasons are the transition between being tilted towards and away from the sun. 15. What are the main aspects of our Earth that affect the seasons. The Earth is round. Sunlight travels in straight lines so it hits parts of the Earth directly giving the maximum amount of heat. Where the Earth hits indirectly there is less heat as the same amount of heat has to heat up a larger area. The Earth is tilted. This means that at certain times of the year parts of the Earth are tilted towards the sun and parts are tilted away from the sun. The Earth revolves around the sun, placing certain areas in direct sunlight at certain times of the year. 16. Explain why locations at the middle of the Earth (equator) are hotter than those areas near the poles. The middle of the Earth (equator) is always in direct sunlight so it always receives the most heat. 17. When does a hemisphere experience summer? Winter? Summer; when it is tilted towards the sun. Winter; when it is tilted away. 18. Explain the significance of the summer and winter solstices and spring and fall equinox. Why did they choose the specific days? Fall and Spring equinox ‘s occur on the days that have exactly 12 hours of sunlight and 12 hours of night. The winter and summer solstices occur on the shortest and longest days of the year. It is related to the degree of tilt towards or away from the sun. 19. Explain the evolution of the Earth using the Big Bang Theory. • It states that the universe began forming 15 to 20 billion years ago, following an enormous explosion. • The dust and gas created as a result of the explosion were drawn together by gravitational attraction to form a huge cloud. • The debris in this gigantic swirling cloud began to gather in circular movements called eddies. • The largest eddies contained enough matter to form whole galaxies. 20. Why do we see light from the moon? Reflection of the light from the sun 21. How long is a lunar cycle? 29.5 days 22. Explain why we see changes in the shape of the moon. Is the moon really changing shape? The moon travels around the Earth, as the Earth travels around the Sun. The moon appears to change shape because the illuminated part of the moon is the part of the moon that reflects the light from the sun. The Earth’s shadow blocks a portion of the sun’s light depending on where the moon and the Earth are in their rotation. This gives the impression that the moon is changing shape when in reality it is not the shadow from the Earth is changing. 23. List, draw and describe the stages of the moon. New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, Waning Crescent 24. Define: Waxing, Waning, Crescent and Gibbous. Waxing: Getting Bigger, Waning: Getter smaller Crescent: Less than half, Gibbous: More than half 25. When we see a full moon what stage of the lunar cycle it the moon in? The moon is half way through the lunar cycle. We only see the half of he moon that is illuminated. 26. What is a star? A star is a luminous globe of gas producing its own heat and light by nuclear reactions (nuclear fusion). 27. What does the brightness of a star depend on? The size and closeness to Earth 28. What does the colour of a star indicate? Describe a blue star. The colour of a star indicates the temperature. Red stars are cool, yellow hotter, blue stars are hot and white stars are the hottest. 29. Describe the life cycle of each type of star. (You can use a diagram to help) Nebula Low Mass Star red Dwarf White Dwarf Nebula Intermediate Mass Star Red Giant White Dwarf Nebula Massive Star Supergiant Supernova 30. Describe a supernova. This is the explosive death of a star, and often results in the star obtaining the brightness of 100 million suns for a short time. Supernovas cause neutron stars and black holes.