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Chemistry Module 3: Chapter 7
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- 1How are elements aranged in the periodic table? State the trend in: atomic number? groups?-They are arranged in order of physical and chemical properties
-Atomic number increase as you go across the period gaining an extra proton as you go along. The groups all have the same number of electrons in there outer shell and differ in number of total shells. - 2What is the term used to describe repeating trends/properties across a period? What is periodicity? Give some examples of periodicity?-This is known as periodicity
-Periodicity is the repeated trends across a period.
-The atomic radius decreasing, having the same number of electron shells, and increasing atomic number. - 3Explain the trends of electron configuration across a period? Explain trends down groups?-At the start of a period a new shell is formed, an electron is placed inside the s orbital. As you go across the period the number of electrons increases by one because of the increase in atomic number
-As you go down the group the number of electrons on the outer shell remains the same and the only difference being the number of shielding shells - 4What are the 4 blocks on the periodic table and where are they?
- 5Where in the periodic table are Alkali metals Transition metals Halogens Noble gases found?
- 6What do ionisation energies tell us? What is the first ionisation energy?-Ionisation energies tell us how easily an atom losses an electron to form a positive ion
-The first ionisation energy is the energy needed to remove 1 mole of electron from 1 mole of gaseous atom to make 1 mole of gaseous 1+ ions
Na (g) ----> Na+ (g) + e- - 7What factors affect the ionisation energy? And explain how these factors do it.-Atomic radius, the greater the distance between the nucleus and outer electrons the less attraction there is and the less energy is required to break the bond
-Nuclear charge, as the number of protons increase the attraction between the outer electrons and the nucleus increases. Greater attraction means more energy is needed to overcome the attraction therefore more energy is needed to remove an electron from its outer shell
-Electron shielding, the more shielding shells there are between the nucleus and the outer electrons the more repulsion there is between electron shells meaning there is a weaker attraction with the nucleus so less energy is needed to remove an electron - 8What is the second ionisation energy?-The energy required to remove 1 mole of electron from 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions.
- 9How would you describe Ionisation energies from a graph? (Example behind is fluroine)
- 10Make a prediction on the element from the table of ionisations.
- 11What are the trends in first ionisation energy down a group? Explain why.-As you go down the group the ionisation energy needed to remove an electron decrease.
-This is because as you go down the group the number of shielding shells increases, this means there is more repulsion between the shells causing a greater distance between the outer electrons and the nucleus. Meaning the atomic radius is larger so the charge is more spread out. Even though the nuclear charge is increasing, this factor is outweighed by the atomic radius and shielding shells, therefore less energy is needed to remove electrons from the outer shell. - 12What are the trends in first ionisation energy across a period? Explain why.-As you go across a period the ionisation needed to remove an electron increases.
-This is because as you go across the period, they all have the same number of electrons shells, the number of protons increases which attracts the outer electrons more closely. This decreases the atomic radius so the charge is spread across a smaller area of space. - 13What 4 groups don't follow the trends for ionisation energy? Explain why.-Group 2 and 3/Group 5 and 6
-This is due to the subshell structure of the groups. Group 3 elements end in p^1 orbitals where as group 2 end in s^2 orbitals. And because p orbitals have higher energy than s which causes them to slightly further away from the nucleus, combined with the extra shielding of the orbitals before it, these factors outweigh the increased nuclear charge explaining why group 2 have higher ionisation energies. - 14Explain why group 5 and 6 elements don't follow the trend of periodicity.-This is because of the outer sub shells in group 5 in the outer electron shell, all the p orbital occupy a single electron. Where as in group 6, one of the p orbitals contains 2 electrons which are spinning in opposite directions and repelling each other. Because of this repulsion between the two electrons, less energy is needed to remove a electron form its outer shell.
- 15What state are all metals at room temperarture? Which metals dont follow this trend? What property do all metals have? What are the 4 main types of chemical bonding?-They are all solid at room temperature except Mercury.
-They can all conduct electricity
-Weak IMFs, Metalic bodning, Ionic bonding and covalent bonding - 16What is metallic bonding? How are metallic bonds formed?-Metallic bonding is the electrostatic attraction between the cations in a metal structure and its sea of delocalised electrons
-They are formed when the metal atoms each donate their outer electrons to form the sea of delocalised electrons which are free to move within the strucuture. - 17How are metal structures maintained? Why do metal structure not have charges?-Because only the sea of delocalised electrons are allowed to move and the cations remain fixed in place which holds the structure togther
-This is because the cations are balanced by the number of electrons therefore therefore there is no charge - 18Describe and explain metallic bonding?-Metallic bonding is when each metal atom donates it outer shell electrons to the delocalised sea of electrons which are mobile and spread throughout the whole structure
-The Cations formed from this form a strong electrostatic attraction with the delocalised electrons (The cations do not move)
-Because the protons and electrons balance, there is no charge - 19What properties do most metals have? What is giant metallic lattice?-Strong metallic bonds
+Conductors of electricity
+High/boiling point
+Malleable and ductile
-A giant metallic lattice is a large group of metal ions (Cations) which are bonded electrostatically to the surrounding sea of delocalised electrons via strong metallic bonds - 20What states can they conduct electricity in? How do metals ions conduct electrictity?-Liquid, and Solid states
-When a voltage is applied to a metal, the sea of delocalised electrons moves the electrical current across the structure to the opposite end of the applied voltage (the positive end) - 21How is the conductivity of electricity in metallic compounds different to ionic compounds?-In ionic compounds, the conductivity of electricity is due to the movement of the ions itself acting as the current. Where as in metallic compounds electricity is conducted via the movement of the electrons acting as the current in which the ions stay in position.
- 22What determines the melting/boiling point of metals? Why do metals have high melting and boiling points? Why are metals insoluable in water?-They are determined by the strength of the metallic bonds
-Most metals have high melting points because they have strong metallic bonds so high amounts of energy are required to overcome the electrostatic attraction and break the bonds
-This is because the metal are held very closesly together by metallic bonds which cannot be overcome easily by the polar water molecules. (I.E the cations attraction to the electrons is stronger than the attraction with the water molecules) - 23What are Giant Ionic Lattice? What are Metalic Latiice?-Ionic compounds are metals and none metals with opposing charges which are electrostatically attracted to eachother.
-Metallic compounds are compounds which only contain metal ions surrounded by a sea of delocalised electrons which they are electrostatically attracted too. - 24What are Simple Molecular Lattices/substances? What are Giant Covalent Lattices?-Simple molecular lattices are none metal compounds in which the atoms are joined together by the sharing of 1 or more pairs of electrons (Covalent bonding). And the molecules held together by weaker IMF's.
-Giant covalent lattices are many non metallic elements which are bonded covalently within a giant structure holding it together
(Giant covalent lattices are only non metals which are solid at RTP) - 25Name examples of: Giant Ionic Lattices. Giant Metallic Lattices. Simple Molecular substances. Giant Covalent lattices.-NaCl MgO, CaCl, KBr
-Mg, Na Ca, K
-F4, Cl2, H2O, CO2
-Graphite, Graphene, Diamond, SiO2 - 26Explain if the following conduct electricity and how they do it. -Metals -Ionic compounds -Simple molecular lattices -Giant Covalent lattices-Ionic compounds can as their charged ions move acting as a current
-Metals can as their sea of delocalised electrons act as a current
-Simiple molecules cannot conduct electricity as they dont have any charged particles or free electrons to carry the current
-Only Graphite and Graphene, this is because their carbon atoms only use 3 of their 4 bonding electrons and the last one is delocalised which is then used to make a current. - 27Explain if the following are soluable in water, and why. -Metals -Ionic compounds-Metals are insoluble in water because they are solids and their atoms are held very closely together by metallic bonds which are hard for polar water molecules to overcome.
-Ionic compounds are soluble as they polar water molecules attract the charged ions more strongly and pull them out of the lattice dissolving them - 28Explain if the following are soluable in water, and why. -Simple molecular lattices -Giant Covalent lattices-They are insoluble in water unless they are polar molecules I.e CO2
-They are insoluble because the covalent bonds holding the atoms together are two strong for the water molecules to overcome. - 29What is Graphite?Graphite is an allatrope of carbon. It is multiple layers of graphene ontop of eachother, which are held together by weak IMFs, where as each carbon has 3 bonding pairs and 0 lone pairs (strong covalent bonds) and a free electron which is delocalised. Because of the delocalised electrons graphene layers can form IMF bonds with other layers of graphene making graphite. In is giant covalent lattice structure they are describe as hexagonal layers. Bond angle 120, trigonal planar.
- 30What is Graphene?Graphene, is an allatrope of carbon, it is a single layer of graphite, in which all the atoms are bonded strongly by covalent bonds. Each carbon has 3 bonding pairs and 0 lone pairs and a free delocalised electron. In its giant covalent lattice it is describe as a long hexagonal layer. It is trigonal planar with a 120 bond angle.
- 31What is diamond?Diamond, is an allatrope of carbon, in which all the atoms are bonded strongly by covalent bonds. Each carbon uses 4 bonding pairs and 0 lone pairs in which it uses all of them in its giant covalent lattice. It has 4 bond angles making it tetrahedral with a bond angle of 109.5.
- 32What explain the trend in melting point across a period?-From group 1 to group 4 the melting point increase, this is because they are transition metals and they can all form metallic bonding
-There is a sharp decrease in melting point between group 4 and 5 because of the transition to elements which giant covalent molecules.
-Groups 5-8 have low melting points, because these elements only form weak IMF - 33—
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- A level Chemistry (Generals) Karteikarten am Chemistry Module 3: Chapter 7, erstellt von BUKDABOSS . am 20/06/2018.
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