...Pure chemical substances are classified as ionic, metallic, covalent molecular and covalent network. In this essay I will describe the nature of each bonding present in these different types of substances and use this to explain the physical properties they exhibit and their structures. Ionic compounds are compounds that are composed of positive and negative ions. An ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Usually, the positively charged portion consists of metal (cations) and the negatively charged portion is an (anion) or polyatomic ion. Ions in ionic compounds are held together by the electrostatic forces between oppositely charged bodies. The positive and negative ions in these compounds are thought to be arranged in an orderly three-dimensional lattice. For example, the structure of sodium chloride is shown. In the lattice, each positive sodium ion is surrounded by six negative chloride ions and each negative chloride ion is surrounded by six positive sodium ions. The position of the ions is fixed and apart from vibration about these fixed positions no other movement of the ions occurs in the solid compound. Each ion in an ionic solid is held in the crystal lattice by strong electrostatic attractions to the oppositely charged ions around it. These electrostatic forces between the positive and negative ions are called ionic bonds. Because ionic compounds have high melting points, in other words considerable...
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...are the covalent bonds and ionic bonds. Covalent bonds are bonds in which one or more pairs of electrons are shared by two atoms. Covalent bonds, in which the sharing of the electron pair is unequal, with the electrons spending more time around the more non-metallic atom, are called polar covalent bonds. In such a bond there is a charge separation with one atom being slightly more positive and the other more negative, i.e., the bond will produce a dipole moment. On the other hand, Ionic bonds are bonds in which one or more electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other. In the extreme case where one or more atoms lose electrons and other atoms gain them in order to produce a noble gas electron configuration, the bond is called an ionic bond. Covalent bonding is a form of chemical bonding between two non-metallic atoms which is characterized by the sharing of pairs of electrons between atoms and other covalent bonds. Ionic bond, also known as electrovalent bond is a type of bond formed from the electrostatic attraction between oppositely charged ions in a chemical compound. These kinds of bonds occur mainly between a metallic and a non-metallic atom. In Chemical Bonds, the principle “like dissolves like” is always abided. To verify the above concept, an experiment was conducted with the following objectives: (1) identify ionic and covalent compounds based on certain physical properties, (2) differentiate...
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...Which of the following groups contains only covalent molecular substances. (a) KOH; NH3; CO2 ; NH4Cl (b) NH4Cl; Cl2; H2S; H2SO4 (c) HNO3; H2SO4; SO2; Na2O (d) H2O; H2S; NH3; CH4 4. The physical properties of solid metals can best be explained proposing that: (a) each metal atom is bonded in the crystal lattice by covalent bonds. (b) positive metal ions are arranged in an orderly way, with valence electrons free to move through the crystal lattice. (c) positive and negative metal ions are arranged in an orderly way, with mobile valence electrons able to immigrate easily around the crystal lattice. (d) each metal atom is surrounded by a variable number of valence electrons, which complete a ‘noble gas’ electronic structure in the crystal lattice. 5. Which of these is not a characteristic of most ionic compounds? (a) It is a solid at room temperature. (b) It has a low melting point. (c) When melted it conducts an electric current. (d) It is composed of metallic and non-metallic elements. 6. A single covalent bond is: (a) not electrostatic in character. (b) the force between two oppositely charged ions. (c) the force between two atoms through the sharing of a pair of electrons. (d) the force between two atoms through the sharing of two pairs of electrons. 7. A major difference between ionic and covalent molecular compounds is that, in...
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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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...Assignment 3: Mixtures, Compounds, Elements, Ionic and Covalent Bonds By: Karen Owens November 17, 2012 SCI 110 Professor Lawrance Mullen 1. Describe the difference between a mixture and a compound. The difference between a mixture and a compound is that a mixture is a substance made by mixing other substances together. Most of the time two or more substances that are chemically united and they do not exist in fixed proportions of each other. Unlike a compound a mixture can be physically separated into pure compounds or elements. For example a cake is made up of different substances that are mixed together that are separated. A compound on the other hand is just the opposite of a mixture. A compound has a constant composition with fixed ratio of elements. It can have properties different from its constituents as a new substance is formed when they are chemically combined. The difference is that a compound can only be separated by chemical methods. That is like taking platinum and gold and melting them both down together. You get platinum gold which is a mixture of two elements combined together. 2. Suppose that you have a pure substance. How can you tell whether it is a compound or an element? You can tell the difference because a compound is a mixture of two or more elements. An element on the other hand is a single thing. It is actually divided into pure substances and mixtures. When we have two or more things that are not chemically combined that is called...
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...1. Atom The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons Atoms are made up of three basic particles: Protons-carries a positive charge Neutrons-carry no charge Electrons-carry a negative charge and encircles the nucleus. (http://education.jlab.org/atomtour/listofparticles.html) 2. Element A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. http://en.wikipedia.org/wiki/Chemical_element 3. Compound A chemical compound is a pure chemical substance consisting of two or more differentchemical elements[1][2][3] that can be separated into simpler substances by chemical reactions.[4] Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms[3] that are held together in a defined spatial arrangement bychemical bonds. Chemical compounds can be molecular compounds held together bycovalent bonds http://en.wikipedia.org/wiki/Chemical_compound 4. Mass number The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. http://en.wikipedia.org/wiki/Mass_number 5. atomic number the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus...
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...time, in a periodic table by using properties of these elements and their compounds and used his table to predict the existence and properties of some elements not then discovered ● Classify elements as metals or non-metals according to their position in the periodic table ● Describe the structure of an atom as a nucleus containing protons and neutrons, surrounded by electrons in shells (energy levels) ● Demonstrate an understanding that the nucleus of an atom is very small compared to the overall size of the atom ● Describe atoms of a given element as having the same number of protons in the nucleus and that this number is unique to that element ● Recall the relative charge and relative mass of a proton, a neutron and an electron ● Demonstrate an understanding that atoms contain equal numbers of protons and electrons ● Explain the meaning of the terms, atomic number, mass number and relative atomic mass ● Describe the arrangement of elements in the periodic ● Demonstrate an understanding that the existence of isotopes results in some relative atomic masses not being whole numbers ● Calculate the relative atomic mass of an element from therelative masses and abundances of its isotopes ● Draw the electronic configurations of the first 20 elements in the periodic table as diagrams and in the form 2.8.1 ● Describe the connection between the number of outer electrons and the position of an element in the periodic table Topic 2 Ionic compounds and analysis ● Demonstrate...
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...electrons. 2. properties of an atom; charges (anion & cation), atomic number, atomic mass & isotopes. 3. determine the number of subatomic particles in a neutral atom and charged atom. 4. the development of atomic models including, the Dalton, Thomson, Rutherford, and Bohr. 5. represent elements using the modified Bohr model of an atom. 6. examine the spectra of common atom(s) to determine that each element has a unique pattern of light emitted & absorbed. 7. model and explain Rutherford’s gold foil experiment. 2. PERIODIC TRENDS I can… 8. describe how elements are organized on the periodic table. 9. identify metals, non-metals and metalloids on the periodic table. 10. identify elements that belong in the same group/family and explain shared characteristics. 11. identify alkali metals, alkaline earth metals, halogens and noble gases on the periodic table and describe their distinguishing characteristics. 12. identify and predict physical and chemical properties of elements based on their location on the periodic table. 13. determine the number of valence electrons for a given element. 3. BONDING & COMPOUNDS I can… 14. define and illustrate ionic bonds. 15. given a compound’s name, determine the ionic formula. 16. use the periodic table to predict what ionic formula will result when two elements bond. 17. show how ions with different charges can form 3-D lattices. 18. name an ionic compound by...
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...Back Print Name Class Date Assessment Chapter Test B Chapter: Chemical Bonding PART I On the line at the left of each statement, write the letter of the choice that best completes the statement or best answers the question. ______ 1. An ionic bond results from electrical attraction between a. cations and anions. b. atoms. c. dipoles. d. orbital. ______ 2. A nonpolar covalent bond is unlikely when two atoms of different elements join because the atoms are likely to differ in a. density. b. state of matter. c. electronegativity. d. polarity. ______ 3. Bond length is the distance between two bonded atoms at a. their minimum potential energy. b. their maximum kinetic energy. c. their maximum potential energy. d. one-half the diameter of the electron cloud. ______ 4. To draw a Lewis structure, it is not necessary to know a. which atoms are in the molecule. b. bond energies. c. the number of valence electrons for each atom. d. the number of atoms in the molecule. ______ 5. For multiple covalent bonds to form in molecules, the molecules must contain carbon, nitrogen, or a. chlorine. b. hydrogen. c. oxygen. d. helium. ______ 6. The principle that states that atoms tend to form compounds in which each atom has eight electrons in its highest occupied energy level is called the a. rule of eights. b. configuration rule. c. Avogadro principle. d. octet rule. Copyright © by Holt, Rinehart and Winston. All rights reserved. Modern Chemistry 51 Chapter Test Back ...
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...known object or substance. They are composed of two elements that combine with each other. They can also be more than two elements. Compounds are one of three forms of matter, and the other two are element mixtures. Compounds have a definite composition, as water will always consist of 88.9% oxygen and 11.1% hydrogen. In contrast, the elements that make up a mixture of iron and sulfur are black iron granules and yellow sulfur crystals which are recognizable. By use of a magnet, iron can be removed from the mixture, and sulfur can be dissolved. In addition, iron and sulfur can be mixed together by just stirring them together (Clarified, 2011). Suppose that you have a pure substance. How can you tell whether it is a compound or an element? A pure substance is an element that cannot be broken down by chemical techniques, like heating, cooling, or reactions from chemicals. This type of pure substance has only one atom, like copper, gold or silver. A large chunk of gold will have millions of gold atoms, and no other atom exist in it. Take for example if you were to heat up copper to the point you melted it, the smallest unit of copper, called an atom is still copper, regardless if it is a solid, liquid, or gaseous state. The atom is the smallest subdivision of an element, but it will maintain the property of the pure substance (Clarified, 2011). What is the difference between an ionic and a covalent bond? Two ions with opposing charges is an ionic bond, they attract...
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...difference between ionic and covalent compounds and understand how their properties give rise to this categorization Introduction: It is amazing what early chemists accomplished even without an understanding of atomic make-up. Reading old chemistry textbooks shows how they justified some of their conclusions, which, with a few exceptions, were right on target. Some discussed the octet rule in terms of “valencies”, and they have it exactly right. What is interesting about this is that at that time they talked about this new sub-atomic particle that they were tentatively calling the “electron”. Another thing they had correct was the categorization of compounds into “covalent” and “ionic”. In class, you have discussed these compounds in terms of electrons, wherein ionic compounds transfer electrons and covalent compounds share electrons. How did the early chemists classify compounds, though, when they did not know what electrons were? They used properties, such as solubilities, melting points, and conduction. Solubility helps us to classify compounds as polar or non-polar, because, as a general rule, polar solutes dissolve in polar solvents (like water), while non-polar solutes dissolve in non-polar solvents (like oils). Conductivity means whether or not a compound will conduct electricity when it is dissolved in water. We call these “electrolytes”. An electrolyte will conduct electricity when dissolved in water, while a nonelectrolyte will not. Finally, ionic compounds tend to...
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...Mixtures consist of Physical combinations of any amount of different substances that do not chemically combine in a reaction, While A mixture can be separated into its components by Physical means, such as Filtration, Solution, Distillation, and Magnetism among others. Suppose that you have a pure substance. How can you tell whether it is a compound or an element? Compounds are formed by the Chemical Combination (reaction) of two or more Pure Elements in definite proportions to form totally new substances having very different properties to those of the elements of their make up. Compounds can only be separated by chemical reaction. To tell if it is a compound or an element, you have to know whether it is the element itself, or made up of 2 or more different elements that can be observed by seeing the formula. The two types of bonds are ionic bonds and covalent bonds. In an ionic bond, the atoms are bound together by the attraction between oppositely-charged ions. For example, sodium and chloride form an ionic bond, to make NaCl, or table salt. In a covalent bond, the atoms are bound by shared electrons. If the electron is shared equally between the atoms forming a covalent bond, then the bond is said to be no polar. Usually, an electron is more attracted to one atom than to another, forming a polar covalent bond. Explain why ionic compounds are formed when a metal from the left side of the periodic...
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...Notes: Chapter 2 I) Matter- consists of chemical elements in pure form and in combinations called compounds. A) Elements- a substance that cannot be broken down to other substances by chemical reactions. 1) Hydrogen, oxygen, nitrogen, and carbon make up 96% of living matter. 2) Other 4% include phosphorus, sulfur, calcium, and potassium. They’re called trace elements- those required by an organism in only minute quantities. B) Compounds- a substance consisting of two or more different elements combined in a fixed ratio. 3) Change the properties of the elements that make them up. II) Structure of an atom C) Subatomic particles 4) Atomic nucleus- the middle region of the atom with protons and neutrons. (a) Protons- are positive and weight about 1 Dalton. They’re unique to each element. (b) Neutrons- are neutral and weight about 1 Dalton. 5) Electron cloud (c) Electrons- are negative and are negligible for weight. Responsible for chemical reactions. D) Atomic number 6) Atomic number- number of protons in the nucleus (d) Also tell us the number of electrons in an electrically neutral atom. 7) Mass number- sun of protons plus neutrons in the nucleus of an atom (e) Written as a subscript to the left of an element’s symbol. 8) Atomic mass- the total mass of an atom E) Isotopes- different atomic...
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...Theory The main points of Dalton’s atomic theory, an explanation of the structure of matter in terms of different combinations of very small particles, are given by the following postulates: 1. All matter is composed of indivisible atoms. An atom is an extremely small particle of matter that retains its identity during chemical reactions. 2. An element is a type of matter composed of only one kind of atom, each atom of a given kind having the same properties. Mass is one such property. Thus, the atoms of a given element have a characteristic mass. 3. A compound is a type of matter composed of atoms of two or more elements chemically combined in fixed proportions. The relative numbers of any two kinds of atoms in a compound occur in simple ratios. Water, for example, a compound of the elements hydrogen and oxygen, consists of hydrogen and oxygen atoms in the ratio of 2 to 1. 4. A chemical reaction consists of the rearrangement of the atoms present in the reacting substances to give new chemical combinations present in the substances formed by the reaction. Atoms are not created, destroyed, or broken into smaller particles by any chemical reaction. Main Points of the Bohr Model Postulate 1: An electron in an atom moves in a circular orbit under the influence of coulomb attraction between the electron and the nucleus obeying the rules of classical mechanics. Postulate 2: An atom can exist in certain allowed or stationary states, with each state having a definite value for...
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