...STUDENT STUDY GUIDE FOR 8TH GRADE CHEMISTRY Welcome to chemistry. Chemistry is the science of matter and its interactions. Everything around you is made of atoms – atoms and their chemical combinations, molecules. Everything you can see, touch, smell, and taste is made up of chemicals. So, the science of chemistry is a very wide ranging science. Parts can concentrate on how interactions of atoms and molecules allow the nerves in your body to conduct electrical signals. Other parts might concentrate on analyzing clues left by a burglar in order to help the police solve a crime. Still, other parts of chemistry might be involved in making new polymers that might be used by the fashion industry to make more colorful and longer wearing fabrics. If you have access to a computer and the internet, there are a number of excellent tutoring sites to help students gain a better understanding of chemistry. One of the better sites for middle school students Is: www.chem4kids.com/ This site is written at middle school level and has a number of on-line tests that you can use to check your understanding of the material. Several other good internet sites are: http://chemistry.about.com/od/chemistry101/Chemistry_101_Introduction_to_Chemistry.html - Chemistry 101 - a collection of articles and on-line help sites in chemistry http://library.thinkquest.org/10429/low/indexl.htm - ChemWeb on line - an introductory chemistry course on line http://library.thinkquest.org/2923/ - Chemistry...
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...700-word paper in which you describe the periodic nature and properties of atoms and molecules. Explain at a level of detail Dmitri Mendeleev would have understood how halogens and alkali metals are extremely reactive, whereas noble gases are not reactive. Compare properties of molecules formed from atoms in similar families; for example, H2S versus H2O. Explain what is meant by the electronic structure of atoms. How does knowing the electronic structure of atoms aid chemists in predicting chemical reactions? Periodic Table is designed to help us understand how elements are going to react to each other and also gives us the breakdown of how many atoms are in each element. This chart also helps us to identify metals, liquids, and gases. This chart shows us the atomic mass and structure of each element. Knowing this information allows us to determine which elements can bond and interact with each other. Alkali metals and halogens can form ionic bonds easily which involves the transfer of an electron from an atom of metal forming a positively charged species, to an atom of non-metal forming a negatively charged species. These two species interact electrostatically and form one of the two extreme forms of bonding; covalent bonding is the other extreme form (Kostiner & Jespersen, 2003). Electronic structure is another piece of important information that you will find on the Periodical Table, this is the atomic number and it will tell you how many atoms make up the element. Alkali...
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...1. How many elements are essential? a. Approximately 20-25% of the 92 natural elements are considered essential, this is about 17-25 elements. 2. Which elements make up 96% of matter on earth? a. The four elements that make up 96% of all matter are the elements oxygen (O), hydrogen (H), nitrogen (N), and carbon (C). 3. What subatomic particles are found in the atomic nucleus? What are their charges? a. There are three subatomic particles found in an atom’s nucleus and they are electrons, protons, and neutrons. Both electrons and protons are electrically charged, electrons are negatively charged and protons are positively charged. The neutron has no electrical charge at all, lending to its name. 4. Explain matter’s state of potential energy....
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...Name Lab Section Date The Mole Concept and Atomic Weights Text Reference: Tro, Chemistry: Structure and Properties Section 2.8 - Atoms and the Mole: How Many Particles? Section 1.9 – Atomic Mass: The Average of an Element’s Atoms The purpose of this activity is to better understand the concepts of relative atomic mass, counting by weighing and the mole. Per cent composition and average atomic mass are included. Part I. Relative Atomic Masses and the Mole – Early Method When John Dalton proposed his atomic theory, he stated that the atoms of each element had a characteristic mass. He carried out experiments to determine the relative atomic mass of each element. To do this, he had to establish a standard because a single atom was too small to weigh. The standard he chose was that the mass of hydrogen would be set equal to 1.000. In a simple experiment, Dalton would measure the grams of an element such as sulfur that reacted with 1.00 gram of hydrogen. For sulfur, the reacting mass was found to be 32.0 grams, and so 32.0 was the relative mass of sulfur with respect to the standard hydrogen. (Note: The current standard for atomic mass is the most abundant isotope of carbon, C-12, with an assigned mass of exactly 12.000 amu.) The following activity will demonstrate how the relative mass method works. 1. Weigh five of the red color balls to three decimal places. Be sure to tare out the mass of the plastic cup. Record the mass in the table below. 2. Weigh five...
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...Atoms, Molecules, and Elements Paper Candace Jefferson March 8, 2016 Charles Chau Chem/110 Atoms are the smallest particles and have the resemblance properties of an element they cannot be broken down and this is considered the building blocks. The atom has a nucleus that is surrounded by electrons. An atom can be negatively or positively charged just depends on the surrounding particles. Molecules are formed when there is a group that is formed and then they are bonded together. It will all depend on how they are bonded that will determine the type of element that will be formed. The periodic table was created by a Russian chemist by the name of Dimitri Mendeleev. He created this table so that everyone would be able to see all of the things that he is able to see. This table is used all through the school system helping people all over the world understand chemistry and making it a lot easier. He wanted it to be organized in a way so that it will be in a group separating certain characteristics. The main purpose of the periodic table was to show the chemical properties explaining the similarities and the differences between everything that he would have on the periodic table. “Mendeleev...
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...paper, leaving the residue on the impermeable substance/filtrating medium and the filtrate to pass through. | Dissolved solids in liquids Evaporation | If the liquid in the mixture is more volatile (boiling point is lower) than the soluble solid, the soluble solid will remain while the liquid evaporates. The procedure employs the use of an evaporating dish and a Bunsen burner. | Crystallisation | Another method of dissolved solids from a liquid mixture (solution)The impure salt is dissolved in water at a high temperature to create a concentrated solution.The mixture is then cooled and the salt crystallises, leaving the impurity in the solution.This crystallised slat contains much less of the impurity than before. The salt can then be filtered and dried.Sugar cane industry. | Assess separation techniques for their suitability in separating examples of earth materials, identifying the differences in properties which enable these separations Yes, fractional distillation can separate a mixture of oxygen and nitrogen because they have similar (but not the same) boiling points. Could filtration successfully separate sand from a sand-salt mixture? No. Without water the salts in the sand and salt mixture will not separate out via filtration because filtration requires an insoluble solid plus a liquid mixture, which in this case would be salt + water Describe situations in which gravimetric analysis supplies useful data for chemists and other scientists * the process...
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...Molecular Structures Molecular Structures Learning Objectives: - Understand covalent bonding displayed by elements in biological systems - Apply the octet rule - Practice converting molecular formulas into molecular structures - Be able to visualize and draw three dimensional molecular shapes Introduction: The octet rule states that most elements will share or exchange valence electrons in order to achieve a similar electron arrangement to the nearest noble gas. This concept is extremely important because it explains why elements bond to form compounds such as water, electrolytes, DNA, proteins and other biologically important substances. In this lab we will be focusing on a small palette of biologically important elements and studying how they covalently bond. In covalent compounds, the behavior of these elements tends to be consistent and predictable. Group Electron Arrangement Number of Bonds and Lone Pairs 1A 7A 1 bond and no lone pairs H X 6A X = F, Cl, Br or I O O O 6A Version: 3/22/16 S 1 bond and 3 lone pairs in biological systems Oxygen generally has 2 bonds and 2 lone pairs, but may have one bond and 3 lone pairs in anions such as hydroxide, or 3 bonds and 1 lone pair in cations such as hydronium. Sulfur has 2 bonds and 2 lone pairs in biological systems. Page 1 of 8 Molecular Structures 5A N Nitrogen generally forms 3 bonds with 1 lone pair, but may form 4 bonds with no lone pairs in cations...
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...Atoms, Molecules and Ions. AN ATOM is the smallest particle of an element. They cannot be split into smaller particles in chemical reactions. Iron is made of iron atoms (Fe). Sulphur is made of sulphur atoms (S) A MOLECULE is a small group of atoms joined together. The atoms may be the same (e.g. O2) or different (e.g. H2O). The chemical formula shows the number and type of atoms present. Non-metal compounds are made of molecules: Carbon dioxide contains CO2 molecules Methane (natural gas) contains CH4 molecules AN ION is an atom or group of atoms with an electrical charge (+ or -). Metal compounds such as sodium chloride or copper sulphate contain ions. Sodium chloride is made of Na+ and Cl- ions Copper Sulphate is made of Cu2+ and SO42- ions Note that metals form positive ions while non-metals form negative ions. A solid is represented by (s). e.g. H2O(s) is ice. A liquid is represented by (l) e.g. Fe(l) is molten iron. A gas is represented by (g) e.g. H2O(g) is steam. A solution in water is represented by (aq). Salt dissolved in water is NaCl(aq). You should remember that the common gases are diatomic (have 2 atoms in each molecule). These are Oxygen O2; Hydrogen H2; Nitrogen N2; and Chlorine Cl2. Elementary Particles Atoms are made up of smaller particles called protons, neutrons and electrons. The protons and neutrons cluster together in a small nucleus at the centre of the atom while the electrons orbit the nucleus. The main properties...
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...chemicals. Success in chemistry depends upon developing a strong familiarity with these basic symbols. For example, the symbol "C"represents an atom of carbon, and "H" represents an atom of hydrogen. To represent a molecule of table salt, sodium chloride, we would use the notation "NaCl", where "Na" represents sodium and "Cl" represents chlorine. We call chlorine "chloride" in this case because of its connection to sodium. You should have reviewed naming schemes, or nomenclature, in earlier readings. A chemical equation is an expression of a chemical process. For example: AgNO3(aq) + NaCl(aq) ---> AgCl(s) + NaNO3(aq) In this equation, AgNO3 is mixed with NaCl. The equation shows that the reactants (AgNO3 and NaCl) react through some process (--->) to form the products (AgCl and NaNO3). Since they undergo a chemical process, they are changed fundamentally. Often chemical equations are written showing the state that each substance is in. The (s) sign means that the compound is a solid. The (l) sign means the substance is a liquid. The (aq) sign stands for aqueous in water and means the compound is dissolved in water. Finally, the (g) sign means that the compound is a gas. Coefficients are used in all chemical equations to show the relative amounts of each substance present. This amount can represent either the relative number of molecules, or the relative number of moles (described below). If no coefficient is shown, a one (1) is assumed. On some occasions, a variety...
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...The chemistry of perming & rebonding Some of us have naturally curly hair but want it straightened; others have it naturally straight but want it curly. But whatever the style you like to wear, there's chemistry involved in it! The structure of hair Hair is made mostly of a protein called keratin, which is also present in nails. In hair, keratin molecules are arranged in straight bundles. These bundles are held together by disulphide bonds (-S-S-), which give strength to the hair. Disulphide bonds are made by the amino acid called cysteine. The cysteine of one keratin molecule forms a disulphide bond with the cysteine of the neighbouring keratin molecule. The more disulphide bonds there are in a strand of hair, the straighter it is. Ammonium thioglycolate: the perm salt Ammonium thioglycolate (HSCH2CO2NH4) is a compound that can break disulphide bonds. This is because it contains a thiol group (-SH). The thiol group replaces one of the sulphur atoms in the disulphide bond, like this: Keratin-S-S-keratin + 2HS-CH2CO2NH4 --> -HO2CH2CS-SCH2CO2H + 2NH3 + 2HS-keratin When the disulphide bond is broken, the keratin bundles come apart, and hair is weakened. Ammonium thioglycolate is therefore used widely in beauty parlours when customers want their hair re-styled. However, if you use too much of it, or if the reaction is left for too long, you could end up going bald. So do not, ever, try it at home! If you have watched the film Legally Blonde, you'll have seen Reese Witherspoon (acting...
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...surplus made is invested back into the establishment to help towards the development of qualifications and support, which keep pace with the changing needs of today’s society. This mark scheme is published as an aid to teachers and students, to indicate the requirements of the examination. It shows the basis on which marks were awarded by examiners. It does not indicate the details of the discussions which took place at an examiners’ meeting before marking commenced. All examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. Mark schemes should be read in conjunction with the published question papers and the report on the examination. OCR will not enter into any discussion or correspondence in connection with this mark scheme. © OCR 2014 F331 1. Mark Scheme These are the annotations, (including abbreviations), including those used in scoris, which are used when marking Annotation Meaning Blank Page – this annotation must be used...
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...conditioners, are comprised of complex formulas that pertain to the periodic table of elements, chemical reactions, and chemical bonds. The purpose of this paper is to show the relationship between complex, every-day hygienic solutions and their chemistry. Behind these complex substances, are a series of chemical bonds and a variety of chemical and physical properties. Shampoos, soaps, and conditioners are all Arrhenius acids or bases because they are all formed in the presence of water (H2O). Shampoos, which consist of mostly water (H2O), are aqueous solutions that are made up of conditioning agents, protectants, cosmetic ingredients, and functional ingredients and pH varies from brand to brand....
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...weapon, with nearly unlimited destructive power. Fire kills more people every year than any other force of nature. The dangerous thing about the chemical reactions in fire is the fact that they are self-perpetuating. The heat of the flame itself keeps the fuel at the ignition temperature, so it continues to burn as long as there is fuel and oxygen around it. The flame heats any surrounding fuel so it releases gases as well. When the flame ignites the gases, the fire spreads. So it is important that we understand the process of how it works to better protect ourselves from the dangers of fire. People used to considered fire as one of the major elements in the universe, alongside water, earth and air. But fire is really something completely different. Earth, water and air are all forms of matter; they are made up of millions and millions of atoms collected together. Fire isn't matter at all. It's a visible side effect of matter changing form. It’s one part of a chemical reaction. Typically, fire comes from a chemical reaction between oxygen in the atmosphere and some sort of fuel (wood or gasoline, for example). Of course, wood and gasoline don't spontaneously catch on fire just because they're surrounded by oxygen. For the combustion reaction to happen, you have to heat the fuel to its ignition temperature. The sequence of combustion generally goes like this: Something heats the wood to a very high temperature. The heat can come from lots of different things for example a cigarette...
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...Research Did you know that most of the ultraviolet light produced by the Sun is blocked by the atmosphere, but some light does still reach Earth? Ultra violet light can be detected using electronic devices. Important terms that will be discussed in this paper are ultraviolet light, photochromism, chemical reactions, and absolute zero. Ultraviolet radiation is defined as Ultraviolet radiation is emitted by the sun and some of its absorbed by the sun and some of it is absorbed by the o-zone in the atmosphere. Too much exposure to ultraviolet light can be can lead to sunburn, skin cancer, or cataracts (The American Heritage...
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...Year 11 Science Mentoring Task Booklet Things to remember when answering 6 mark exam questions: 1. 2. 3. 4. 5. 6. Try and remember everything you can about what the question is asking before you start answering it Make at least 6 points Write in full sentences starting with capital letters and ending with full stops Try and answer the question in around five minutes Check your answer to make sure you have not left anything out Remember to use key words when appropriate Things to remember when marking 6 mark exam questions: 1. 2. 3. 4. Use a green pen Read through the science points at the bottom of the mark scheme first In the answer put ticks to show where the marks are coming from Mark for spelling and grammar by circling the word or part of the text and writing above it as follows: • • • • 5. 6. 7. 8. Spelling mistake (Sp) Missing full stop (Gr) Missing capital letter (Gr) Poor grammar (Gr) Cross out any bits that are irrelevant to the question Add up their total number of marks If there are more than three spelling or grammar errors minus one mark Leave constructive feedback Biology Cells Tissues & Organs Summary All living things are made up of cells. The structures of different types of cells are related to their functions. To get into or out of cells, dissolved substances have to cross the cell membranes. Cells Cells are the smallest unit of life. All living things are made of cells. Most human cells, like most other animal cells, have the following...
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