Yr 10C Atomic Structure Core Notes PDF

**Atomic Structure Core Notes** In both physical and chemical changes they both cause alterations (some form of change) to the original matter involved. In a physical change **[no new substances are being formed]**. All that changes is the physical state of the material. Eg 1. Melting ice (solid...

**Atomic Structure Core Notes** In both physical and chemical changes they both cause alterations (some form of change) to the original matter involved. In a physical change **[no new substances are being formed]**. All that changes is the physical state of the material. Eg 1. Melting ice (solid to liquid) - ice and liquid water are still the same H~2~O molecules. Eg 2. Dissolving - a solid mixes completely with a liquid to form a solution like dissolving copper sulfate in water. In a chemical change **[a new substance is formed]**, a change occurs at the molecular level (bonds breaking and forming). Signs that a chemical change or chemical reaction has occurred include: colour changes, temperature changes, a gas may be given off, a sound may be heard and change in mass. Chemical changes are often summarised in chemical equations in words or symbols. The reactant(s) (the chemicals you start with) are changed into the products (the new substance(s) made). Eg magnesium + oxygen →magnesium oxide. Mg + O~2~ → MgO In Summary: Rule 1: A chemical change involves producing a new substance (observed by colour changes, fizzing, smell etc) with changes at the molecular level *whereas* a physical change does not. - - - **3. Relate the valence electrons and electron configuration to the group the element is in, in the periodic table.** **Groups:** The Group numbers are at the top of the columns numbered from 1 to 18. All the elements in a group have the same number of electrons in the outer shell (valence shell or orbital) Group 1 = 1 valence electron Group 2 = 2 valence electron Group 13 = 3 valence electrons Group 14 = 4 valence electrons Group 15 = 5 valence electrons Group 16 = 6 valence electrons Group 17 = 7 valence electrons Group 18 = 8 valence electrons Elements in the same group have similar chemical reactions. **Periods:** The elements found in period 2 will have 2 electron shells. (Li 2.1 ; O 2. 6- two electron shells) Period 3 elements have 3 electron shells. (Na 2.8.1 - three electron shells) Period 4 elements have 4 electron shells. (Ca 2.8.8.2 - four electron shells) H = Hydrogen He = Helium Li = Lithium Be = Beryllium B = Boron C = Carbon N = Nitrogen O = Oxygen F = Fluorine Ne = Neon Na = Sodium Mg = Magnesium Al = Aluminium Si = Silicon P = Phosphorus S = Sulfur Cl = Chlorine Ar = Argon K = Potassium Ca = Calcium The above are the first 20 elements. Other elements you should be familiar with are Cu = Copper Ag = Silver Au = Gold Fe = Iron Ba=Barium Br=Bromine Zn = Zinc Pb = Lead The atomic number of an atom shows how many protons it has in its nucleus. The number of electrons an atom has is the same as the number of protons as the atom is neutral overall. The number of neutrons can be calculated by subtracting the atomic number of an atom from its mass number. For example, Li: 3p^+^ , 3e^-^ & 4 neutrons. Atoms have the same number of protons (+1 charge) and electrons (-1 charge). Therefore these cancel each other out and the atom has no overall charge making it neutral. Find B and Al on the Periodic table and draw a line between them, and then form a staircase going down, Label the Metals on the left and Non-metals on the right. Hydrogen is sometimes placed floating above Group 1, but is a non-metal. **.**  - - - Example question: Given the following data, explain which metal would be best suited to make a cooking pot. +-----------------------+-----------------------+-----------------------+ | Metal | lead | Aluminum | +=======================+=======================+=======================+ | Thermal conductivity | 35 | 251 | | | | | | (W/m K) | | | +-----------------------+-----------------------+-----------------------+ | Density | 11.34 | 2.7 | | | | | | ( g/m^3^) | | | +-----------------------+-----------------------+-----------------------+ | Reactivity | Moderate | Low | +-----------------------+-----------------------+-----------------------+ A cooking pot needs to be able to transfer heat easily to the food it needs to cook and therefore should be made of a good thermal conductor. In this case, Aluminium has a higher thermal conductivity than lead so it will be able to heat up faster and cook the food more evenly. Aluminum also has a lower density than lead which makes it a better material to use for a cooking pot as it will be lighter to carry while cooking. It is also important to make the cooking pot with a material that has low reactivity, such as aluminum. If lead was used, it could react with the food being cooked and contaminate the food which can then lead to food poisoning for whoever consumes it. **9. Describe ionic & covalent bonding** Non-metal elements are located on the right hand side of the periodic table and they will form covalent bonds with each other to fill their valence shells. elements. **14.** **Discuss how and why atoms form ions and how this relates to their position on the periodic table** An ion is an atom that has lost or gained electrons to achieve a full outer shell *to become stable*. Elements on the left hand side of the periodic table are metal and typically react to lose their valence electron(s) to form ions. Elements in groups 1-2 will lose their valence electrons to have a full outer shell and become stable. Eg. A magnesium atom is in group 2 because it has 2 valence electrons. To achieve a full shell and become stable, it loses 2 electrons and becomes the magnesium ion Mg^2+^. As protons are positive, and electrons are negative, there are 12 positive protons and 10 negative electrons. There are 2 more positives than negatives, so the charge is +2 overall. Elements on the right hand side of the periodic table are non-metal and typically react to gain electron(s) to form ions. Elements in groups 16-17 will gain valence electron(s) to have a full outer shell and become stable. Eg. An oxygen atom is in group 16 because it has 6 valence electrons, to achieve a full shell and become stable it gains 2 electrons and becomes the oxide ion O^2-^.As protons are positive, and electrons are negative, there are 8 protons and 10 electrons. There are 2 more negatives than positives, so the charge is -2 overall. Notice the only thing that changes with ions compared to normal ions is the number of electrons. The protons and neutrons stay the same **15.** **Write word equations for reactions and state the product and reactant from a word equation** Magnesium reacts with Oxygen producing a bright white flame and leaving a white solid Magnesium oxide behind. **16.** **Write ionic formula for simple compounds and name a compound given the ionic formula** When Metals and non-metals combine in a chemical reaction they make a new compound. These are called ionic compounds, because each atom forms an ion. The ions are attracted to each other due to the positive charge being attracted by the negative charge by electrostatic attraction to form an ionic bond. **Writing ionic formula:**  Barium is in Group 2, so has a +2 charge Chlorine is in Group 17 so has a -1 charge Notice you do not put the 1, at the bottom Of Barium, if you write Ba, it is assumed there Is one of them, and you don't need to write a 1 to show it. This means Barium has lost 2 electrons, and 2 2 Chlorines have each gained 1 electron each. E.g. Ca + O~2~ →CaO In this case both Calcium and Oxygen have the same charges so they cancel. What this actually means, is that one Calcium ion has lost 2 electrons, and one Oxygen atom has gained 2 electrons. E.g. Al + O~2~ → Al~2~O~2~ In this case 2 Aluminium atoms have lost 3 electrons each, a total of 6 electrons. It takes 3 Oxygen atoms to gain 6 electrons, as each oxygen needs to have 2 electrons to get a full outer shell **Naming Ionic Compounds:** Naming Ionic Compounds Rules **Rule 1:** All metal ions have the same names as metal atoms. Positive ions -- are named by naming the metal and adding ion. K^+^ = Potassium ion Li^+^ = Lithium ion **Rule 2:** If it is a simple monatomic ion ("by itself") eg O^2-^ it ends in "ide" O^2-^ = Oxide S^2-^ = Sulfide Cl**^-^** = Chloride F**^-^** = Fluoride **Rule 3:** If it is a polyatomic ion and it has oxygen it ends in "ate" SO~4~^2-^ = sulfate CO~3~^2-^ = carbonate PO~4~^3-^= phosphate **Rule 4:** Learn these exceptions to know.... OH^-^ = hydroxide HCO~3~^1-^ = hydrogen carbonate NH~4~^+^ ­­­= ammonium We always write the metal ion first. Ionic compounds are named by combining the metal and non-metal NaF = Sodium Fluoride MgO = Magnesium Oxide Na~2~S = Sodium Sulfide **17.** **Write a symbol equation using correct ionic formula** Write the correct formula for all of the reactants and products. Make sure that you use an arrow and not an = sign. Know these 5 diatomic elements H~2~, N~2~, O~2~, Cl~2~, F~2~ The other elements have the same symbol as the period table. For any ionic formula follow the instructions on LO 13. Example: Word equation: Magnesium + chlorine → magnesium chloride Symbol equation: Mg + Cl~2~ → MgCl~2~ Working out: Mg^2+^ and Cl^-^ therefore to balance the charges and make a neutral ionic compound we need 2 chlorines to balance the charge of 1 magnesium ion. MgCl~2~