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Chemistry Revision
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WHAT DOES THE STANDARD SAY?
Aspects of acids and bases will be selected from: Atomic structure electron arrangement of atoms and monatomic ions of the first 20 elements (a periodic table will be provided) isotopes ionic bonding names and formulae of ionic compounds using a given table of ions. Properties acids release hydrogen ions in water reactions (of acids with bases) to form salts. pH and effects on indicators. Rates of reaction and particle theory. Uses neutralisation carbon dioxide formation salt formation Acids and bases are restricted to HCl, H2SO4, HNO3, metal oxides, hydroxides, carbonates and hydrogen carbonates.
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WHERE TO BEGIN Know the basics:
Key definitions (ion, isotope, element, compound etc). Names/symbols of ions, elements and compounds The general equations The factors of rates of reactions Where substances fit into the pH scale Positive test for litmus and universal indicators (acid, bases, neutral and strength).
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Can you name these ions?
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Can you name these elements?
Pb Cu Fe Au Ag Ti K P Zn I
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Can you name these compounds?
Ca(OH)2 Al2O3 PbCl2 NH4NO3 BaSO4
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Can you define the following terms?
Ion A charged atom that has lost/gained electrons in their outer shell Isotope At atom of the same element (same number of electrons/protons) but with a different number of neutrons Element a substance made up of only one type of atom Valence electrons electrons in an elements outer shell that can be lost or gained Compound Two or more element chemically combined
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Atomic Structure What are these two numbers and what do they tell us?
24 Mg 12 Atomic number = number of protons Mass number= Number of protons and neutrons How many Protons, electrons, neutrons? 12 protons, 12 electrons, 12 neutrons How will the electrons be arranged? 2,8,2
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Ions and Isotopes What does Al 3+ mean? What has happened to the atom?
Aluminium is an Ion that has lost three electrons (from its outer shell) to be come positively charged by three. It has done this because it still has the original number of protons (13) which are positively charged. What is the difference between 12C and 13C? What is one way the atoms will be physically different? What charge do isotopes have? Why? Carbon 12 has one less neutron than carbon 13. They will have the same numbers of electrons and protons (making the atoms neutral). Because of this extra neutron, carbon 13 will be heavier.
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How do Ionic compounds Form?
What is needed to make an ionic compound? A metal and a non-metal atom What happens when calcium as an ion wants to lose two electrons but chlorine (chloride) can only gain one electron? Two chloride ions will form and join with calcium What charge will this compound have? What will the chemical formula be? Neutral, CaCl2 Give the correct formula for the following compounds: Calcium Hydroxide Iron (ii) carbonate Aluminium Sulphate Ammonium bi-carbonate
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NCEA QUESTIONS- ION Formation
QUESTION ONE: IONS AND IONIC FORMULAE (a) Explain why the ions formed by aluminium and sulphur have a different charge. In your answer you should: • describe an ion • describe the atomic structures of a aluminium ion and a sulphide ion • state the charge on the aluminium ion and the sulphide ion • explain the charges on both ions in terms of electron arrangement and number of protons.
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ISOTOPES Nitrogen can exist in different forms call isotopes. Two of these isotopes are Nitrogen 14 (14, 7) and Nitrogen 15 (15, 7). Explain why Nitrogen 14 and 15 are both neutral atoms. In your answer you should fully describe their atomic structure and electron configuration. You should also describe how they will be physically different.
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Ionic bonding Element Z is between numbers 5 and 12 on the Periodic Table. An atom of element Z forms an ion. This ion combines with the Aluminium ion to form a neutral compound, Al2Z3. Determine what element Z is and justify your answer. In your answer you should: • consider the ratio of Z ions to aluminium ions • use the formula Al2Z3 to determine the charge of the Z ion • explain how you would use the Periodic Table in your Resource Booklet to find out which group element Z is in • name element Z.
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