Identifying an Ionic Compound. Objectives: To learn and test for metal ions and non-metal ions and then apply them to discover the identity of an unknown ionically bonded substance

Identifying an Ionic Compound- Introduction Ionic compounds are defined as being compounds where two or more ions (an atom or group of atoms with an overall electrical charge) are held next to each other by electrical attraction. One of the ions has a positive charge - called a "cation", and the other has a negative charge - called "anion". Cations are usually metal atoms and anions are either nonmetal or polyatomic ions (ions with more than one atom). Usually, when we have ionic compounds, they form large crystals that you can see with the naked eye. Table salt is one of this- if you look at a crystal of salt, you can see that it has in irregular cube shape. This is because salt likes to stack in little cube-shaped blocks. When forming salt, Na readily loses an electron and Cl readily gains an electrons so both can become stable. Heat is added in the reaction so Na burns brightly in CL gas and a white solid forms on the sides of the container. This solid is salt, or sodium chloride. When the chlorine atom gained an electron, the atoms arrange themselves in a lattice. The force of attraction between a cation and anion is a very strong bond called an "ionic bond". This is an electrostatic attraction. An ionic bond happens between a metal and a nonmetal. Properties of salts: 0. All ionic compounds form crystals. 0. Ionic compounds tend to have high melting and boiling

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Chemistry revision notes. Atomic Structure and Bonding, Electrolysis, Acids and Alkalis.

Atomic Structure and Bonding (F) 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 Magnesium Oxide is made of Mg2+ and O2- 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

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Revision of Atomic Structure

Revision of Chemical Bonding Bonding occurs between elements in order that they can obtain stable 'full shell' (noble gas) electron configurations. Types of bonding: ionic, covalent, metallic Ionic Bonding Transfer of electrons to create charged particles called ions Ionic compounds contain positive and negative ions whose charges balance. Usually found in compounds that contain metals combined with non-metals - electrons are transferred from the metals (to leave positive metal ions) to the non-metals (to create negative ions). e.g. sodium chloride NaCl e.g. magnesium chloride MgCl2 (simplified diagram - only outer shells shown) The ions are held together by the strong electrostatic attraction between opposite charges. In the solid they form giant regular structures called lattices. Greater charges generally means stronger forces, so MgO (Mg2+ O2-) has a higher melting point than NaCl. Properties of ionic compounds: Usually solid at room temperature with high melting points and boiling points. Usually hard Usually soluble in water Do not conduct electricity when solid, but can when molten or in aqueous solution because the ions are free to move. Covalent Bonding Sharing of electrons between atoms. Usually between non-metal atoms. Atoms overlap outer shells to create stable full shells. e.g. hydrogen H2 Shared pair of electrons is known as a single covalent

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The Periodic Table - Revision Notes The numbers in italics are the page numbers of where more information can be found in the revision guide.

CD6 The Periodic Table Revision Notes The numbers in italics are the page numbers of where more information can be found in the revision guide. Elements and atom 6 Everything is made up of 100 different chemicals called elements . An element is a pure substance that is only made up of one type of particle called an atom. Each element has its own symbol on the periodic table. Eg Copper = Cu Oxygen=O An atom is made up of two parts. In the centre there is a small , heavy lump with a positive charge called the nucleus. On the outside small light ,negatively charged particles called electrons orbit around the nucleus. Nucleus (+ve) Electrons (-ve) An Atom Each element has two numbers on its symbol. The smaller number is the atomic number and tells you the number of protons in the nucleus of an atom of that element. The larger number is the atomic weight (Ar) . The atomic weight tells you the total number of neutrons and protons in the nucleus. Eg 23 Na The atomic number is 11 . The atomic weight (Ar ) is 23. 7 11 Isotopes are two different atoms of the same element that are only different because they have different

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A discussion of Atoms.

Atoms There are 112 elements although elements 110-112 are as yet unnamed. These 112 elements are organized in the periodic table: The modern chemical symbols were introduced by Berzelius. Rows of elements are called "periods" and columns of elements are called "groups" (1A, 2A 3B etc.). There are three general classes of elements distinguished by their physical properties: the metals (generally shiny and conduct electricity), the non metals (not shiny, sometimes gasses at STP and poor conductors of electricity) and the metalloids (properties in between those of metals and non metals.). Some groups have special names: Group 1A: Alkali metals Group 2A: Alkali earth metals Groups 3B-2B: Transition metals Group 7A: Halogens Group 8A: Noble gases Many of the heavier elements are unstable - which means that the atoms of those elements break apart very quickly. Elements within a group share similar chemical properties. Other chemical and physical properties of the elements can be deduced from their position in the periodic table. The structure of the periodic table and thus their chemical and physical properties is directly related to their atomic structure. Atomic Weights Most elements can be found on earth (with the exception of those elements that too unstable and thus must be synthesized in the laboratory). Since all elements have isotopes then we must consider how

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Covalent bonding

Covalent bonding is an intermolecular form of chemical bonding characterized by the sharing of one or more pairs of electrons between two components, producing a mutual attraction that holds the resultant molecule together. Atoms tend to share electrons in such a way that their outer electron shells are filled - this is referred to as electron configuration. Such bonds are always stronger than the intermolecular hydrogen bond and similar in strength to or stronger than the ionic bond. In contrast to the ionic and metallic bond, the covalent bond is directional, i.e. the bond angles have a great impact on the strength of the bond. Because of the directional character of the bond, covalently bound materials are more difficult to deform than metals. The cause of the directionality is the form of the s, p, d, and f orbitals. In organic chemistry, the directionality of the bonding is often described by hybrid orbitals. Covalent bonding most frequently occurs between atoms with similar electronegativities. For this reason, non-metals tend to engage in covalent bonding more readily since metals have access to metallic bonding, where the easily-removed electrons are more free to roam about. For non-metals, liberating an electron is more difficult, so sharing is the only option when confronted with another species of similar electronegativity. However, covalent bonding involving

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The Sub-atomic particles

Foundation Chemistry The Sub-atomic particles Atoms are made of three main particles: protons, neutrons and electrons. > The protons and neutrons form the nucleus, in the centre of the atom > Protons and neutrons are sometimes called nucleons, because they are found in the nucleus. > The electrons surround the nucleus Properties of the sub-atomic particles PROPERTY PROTON NEUTRON ELECTRON Mass/kg .673 x 10 -27 .675 x 10-27 0.911x 10-30 (very nearly 0) Charge/C (Coulombs) +1.602x10-19 0 -1.602 x10-19 Position In the nucleus In the nucleus Around the nucleus These numbers are extremely small. In practice we use relative masses and charges. Relative atomic mass, Ar The relative atomic mass of an element is the average mass of the naturally occurring isotopes of the element relative to the mass of an atom of 12C (one atom of carbon 12 is given a relative atomic mass of exactly 12) ATOMIC NUMBER, Z=NUMBER OF PROTONS=NUMBER OF ELECTRONS Relative Isotopic mass The relative isotopic mass is the mass of an isotope of an element relative to the mass of an atom of carbon 12 (one atom of carbon 12 is given a relative atomic mass of exactly 12) Relative Molecular Mass, Mr The relative molecular mass of a compound is the mass of a molecule of the compound relative to the mass of an atom of carbon 12 (one atom of carbon 12 is given a relative atomic mass of

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Revision notes on elements, the periodic table and compounds.

ELEMENTS Definition: An element is the basic building block of matter that cannot be broken down further by chemical reaction (This definition was suggested by Robert Boyle). Element can be broken down ONLY by nuclear fission. So far 106 elements have been discovered. Water (H2O) is not an element - because it can be further broken down into 1 oxygen & 2 hydrogen atoms. Carbon dioxide (CO2) is not an element - because it can be further broken down into 1 carbon & 2 oxygen atoms. Atmospheric oxygen (O2) is not an element - because it can be further broken down into 2 oxygen atoms. Note: H2O.......... CO2....... NO2 - these are compounds Every element has: * A name (may vary in different language) - Name may be taken from their Latin name - Name may be taken after the scientist who invented them - Name may be taken after the place where they were found * A symbol (same all over the world) Element Chemical symbol Hydrogen H Calcium Ca Chlorine Cl Iron Fe (from Latin name ferrum) Lead Pb Sodium Na Helium He In Universe: Most abundant element in universe - H (hydrogen) & He (helium) Stars are made of H & He Earth's crust: Most abundant element in earth's crust - O (oxygen = 45%) & Si (silicon= 25%) Others: - Aluminium (Al) = 7% - Iron (Fe) = 5% - Sodium (Na) = 5% - Calcium (Ca) = 4% - Magnesium (Mg) = 3% - Nickel (Ni) = 3% - Potassium

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Chemistry Revision Notes on atomic structure, nuclear power and the periodic table

Chemistry Major Developments of the Atomic Model > About 400BC: Greek philosopher Democritus first suggested that all substances consisted of tiny indestructible particles called atoms. > 1808: An English chemist named John Dalton described his ideas about matter. Dalton's ideas were based on many scientific experiments and observations. Although some of these today are to a degree, incorrect, Dalton's developments formed the early settlements that led to the modern atomic theory. Dalton stated a number of ideas: * All matter is composed of atoms * Atoms cannot be made or destroyed * All atoms of the same element are identical * Different elements have different types of atoms * Chemical reactions occur when atoms are rearranged * Compounds are formed from atoms of the constituent elements. > 1897: English Scientist Sir J.J. Thomson explained that the atom contained negatively charged particles called electrons. He suggested that atoms were positively charged spheres with negatively charged electrons embedded in them like the fruit in a plum pudding. > 1911: Lord Rutherford proposed a nuclear model for the atom. In his model, the atom consisted of mostly space with a dense nucleus containing positively charged protons in the centre. Negatively charged electrons orbited the nucleus. Although Lord Rutherford's model of the atom was essentially the same as today's

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Extracting copper from malachite (copper carbonate) by using a redox reaction

Extracting copper from malachite (copper carbonate) by using a redox reaction Aim Our aim is to extract copper from copper carbonate using a redox reaction. What is a redox reaction Reduction equals loss of oxygen Oxidation is the gain of oxygen O-Oxidation I-is L-loss OF ELECTRONS R-reduction I-is G-gain Prediction When I heat copper carbonate I expect it to turn from green to black because it's changing the copper oxide. The copper carbonate is being reduced. Copper oxide + carbon carbon dioxide + copper 2CuO C CO2 2Cu Black Pink Copper oxide will be reduced to turn into copper as it loses oxygen. This is called a redox reaction. (Science diagrams) Method . Put 1.5g of malachite powder into a large test tube and heat it gently until it turns black and stops rising in the test tube. 2. Allow the tube time to cool 3. Add 1.5g of carbon powder and mix well. 4. Heat the mixture strongly until it turns red and you can see some of the pink copper. 5. Let the mixture cool. 6. Separate the copper from the waste by half filling the test tube with water and pouring the mixture into a beaker of cold water. 7. Leave for one minute and then pour out the dirty water. 8. Keep adding cold water to the mixture and pouring off the dirty water till you see pink copper at the bottom of the tube. 9. Put the copper onto

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