latihan chapter 4 & 5 f4

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    Name : ________________________________________________Class : ________________________________________________

    1.

    (a) Complete the table below that gives information about two ions.

    IonElectron arrangement of

    ionNumber of

    protonsNumber ofelectrons

    K+

    19Cl- 17

    [2 marks]

    (b) In which group and period does the element Cl belong?

    [2 marks]

    (c) Give the formula of the ionic compound.

    [1mark

    ]

    (d) Explain how this compound is formed, in terms of the transfer of electrons?

    [2 marks]

    (e) Explain why this compound has a high melting point.

    [2 marks]

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    2.

    Answer the following questions using part of the Periodic Table shown below.1 18

    H 2 13 14 15 16 17

    Mg 3 4 5 6 7 8 9 10 11 12 Al Si P

    K Fe Ni

    (a) In the Periodic Table above, mark X in the boxes for all thehalogens.

    [1 mark]

    (b) Choose two elements which are transition metals.

    [2 marks]

    (c) Write the electron configuration for potassium (K) atom.

    [1 mark]

    (d) Write the chemical equation for the reaction between magnesium andoxygen gas.

    [1 mark]

    (e) State one reason why helium gas is more suitable to be used inmeteorological balloons than hydrogen.

    [1 mark]

    (f) Which two elements form chlorides of the type XCl3?

    [1 mark]

    (g) Predict the nucleon number of aluminium.

    [1 mark]

    (h) Which element is a metalloid?

    [1 mark]

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    3

    .

    ElementsR and Sreact to form a white solid compound T. The table below provides some

    information aboutR and S.

    Element R Element S

    Proton number 11 8

    Electron arrangement 2.8.x 2.y

    Based on the information in the table, answer the following questions.

    (a)What is the values ofx andy?

    [2 marks]

    (b

    )

    (i) Draw the electron arrangement of compound Tand deduce its formula.

    [3 marks]

    (ii) Is Ta covalent compound or an ionic compound? Explain.

    [2 marks]

    (c)Under what condition(s) will compound Tconduct electricity? Explain.

    [2 marks]

    (d)

    Give one other physical property of compound T.

    [1 mark]

    4.

    The diagram below shows the valence electron arrangement of two elements,Pand Q.

    (a) Element Q does not exist in nature as an element.

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    (i) Give the molecular formula of the compound of element Q that exists in nature.

    [1 mark]

    (ii) State the type of bonding present in this compound.

    [1 mark]

    (iii) Give two physical properties of this molecule.

    [2 marks]

    (b) ElementPcombines with element Q to form a compound.

    (i) State the type of bonding in the compound.

    [1 mark]

    (ii) Write the formula of this compound.

    [1 mark]

    (iii) Write the chemical equation for the formation of this compound.

    [1 mark](iv) Draw an electron arrangement diagram to show the valence electrons of the compound.

    [2 marks]

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    6

    .

    The figure below shows some elements in the Periodic Table which are represented by Q,R, S, T,

    W,Xand Y.

    T

    W R S

    Y Q X

    Answer the questions below.(a) Which element has the smallest size?

    [1 mark]

    (b) Which element is most inactive?

    Explain your answer.

    [2 marks]

    (c) (i) Which of the elements is a metalloid?

    [1 mark]

    (ii) Write the electron configuration for the element.

    [1 mark]

    (d) (i) Which element is a transition metal?

    [1 mark]

    (ii) State two special properties of this element.

    [2 marks]

    (e) Write the chemical equation for the reaction ofWwith water.

    [1 mark]

    (f) Which element is the most electropositive element?

    [1 mark]

    7.

    (a)Sodium, magnesium, aluminium, silicon and sulphur are elements of Period 3 in the PeriodicTable.

    (i) Write down the formulae of all the oxides of the elements given. [3 marks]

    (ii) Classify the oxides in three groups under basic oxide, amphoteric and acidic

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    oxide. [3 marks]

    (iii) Using only hydrochloric acid and sodium hydroxide, explain how to distinguishbetween the three types of oxides. [6 marks]

    (b)

    (i) Transition elements have unique characteristics. State four suchcharacteristics. [4 marks]

    (ii) Both transition metals and alkali metals are typical metals. Compare the reactivity, hardness,

    density and melting points between transition metals andalkali metals. [4 marks]

    8.

    The table below shows some information about noble gases.

    Name Symbol Proton number Boiling point/ C

    Helium He 2 -269

    Neon Ne 10 -246

    Argon Ar 18 -186

    Krypton Kr 36 -152

    (a) Write the electronic configuration of argon.

    [1 mark]

    (b) Explain why the noble gases are inert.

    [2 marks]

    (c) Noble gases have low boiling points. Explain why.

    [2 marks]

    (d) Give two uses of helium.

    [2 marks]

    (e) Do noble gases conduct electricity? Explain your answer.

    [2 marks]

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    9

    .

    The proton number and electron arrangement for the five elements are shown in the table below.

    Element Proton numberElectron

    arrangement

    Hydrogen 1 1

    Carbon 6

    Nitrogen 7

    Oxygen 2.6Chlorine 17

    (a) Complete the table above. [2 marks]

    (b) How is a covalent bond formed?

    [2 marks]

    (c) Give an example of the elements which will form the following covalent bonds among its own

    atoms.

    (i) Single covalent bond.

    [1 mark]

    (ii) Double covalent bond.

    [1 mark](iii) Triple covalent bond.

    [1 mark]

    (d) Draw an electronic structure to represent the formation of oxygen gas and nitrogen gas.

    [2 marks]

    (e) Covalent bonds are also formed between the different atoms of non-metal elements.

    (i) Based on the table, give an example for the formation a single covalent bond between twodifferent elements.

    [1 mark]

    (ii) Predict the melting point of the compound mentioned in (e)(i).

    [1 mark]

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    10

    .

    Explain the following statements regarding the properties of elements in the Periodic Table.

    (a) Noble gases in Group 18 are inert. [2 marks]

    (b) Elements of Group 1 show similar chemical properties but the reactivity of the

    elements increases with increasing proton number. [5 marks]

    (c) The atomic size of an atom decreases from left to right across the period.

    [5 marks]

    (d) Electronegativity of an element increases from left to right across the period.

    [5 marks]

    (e) The metal rubidium, with the symbol Rb, is just below potassium in the Periodic Table.

    (i) How many valence electrons does an atom of rubidium has? [1 mark]

    (ii) What would you expect to see when a small piece of rubidium is added tocold water? [1 mark]

    (iii) Write an equation for the reaction in (iii). [1 mark]

    Answers:1.

    (a)Ion

    Electron arrangementof ion

    Number ofprotons

    Number ofelectrons

    K+ 2.8.8 19 18

    Cl- 2.8.8 17 18

    (b) Group = 17; Period = 3

    (c) KCl(d) Each atom of potassium loses one electron to an atom of chlorine to form a positive

    ion, K+ and a negative ion, Cl-.

    (e) The opposite charged ions, K+ and Cl-, are held together by strong electrostaticforces of attraction. As the results, a lot of heat energy is required to overcome these

    forces. Hence, KCl has a high melting point.

    2.

    (a) Group 17

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    X

    X

    X

    (b) Fe and Ni(c) 2.8.8.1

    (d) 2Mg + O2 2MgO

    (e) Helium is inert and non-flammable.(f) Al and P

    (g) 27

    (h) Si

    3.

    (a) x = 1,y = 6

    (b) (i)

    (ii) It is an ionic compound because it made up of ions of metalR and non-metal S.

    (c) It conducts electricity in the molten state or in the aqueous state because it has

    mobile ions.(d) It has high melting point and boiling point or it dissolves in polar solvents, e.g. H2O.

    (any one)

    4.(a)(i) Q2

    (ii) Covalent bond

    (iii) 1. It has low melting point and boiling point.2. Poor conductor of electricity.

    (b)(i) Covalent bond

    (ii) PQ2(iii

    )P+ Q2 PQ2

    (iv)

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    5.

    (a)B andD(b)B2+

    (c)AtomD donates one electron to attain the octet stable electron arrangement, ionD+.

    (d)C+ e C-

    (e) (i) Ionic bond

    (ii)

    (iii)

    AtomFhas achieved octet stable electron arrangement. Hence, it unable to receiveelectron from atomD.

    6.(a) T

    (b) Sbecause all its orbitals are completely filled with electrons.

    (c) (i) R(ii) 2.8.4

    (d) (i) Q

    (ii) It forms coloured compounds.

    It has various oxidation numbers.(e) 2W+ 2H2O 2WOH + H2(f) Y

    7.

    (a) (i) Na2O, MgO, Al2O3, SiO2, SO2, SO3 [3 m]

    (ii) Basic Amphoteric Acidic

    Na2O, MgO Al2O3 SiO2, SO2, SO3 [3 m]

    (iii) Basic oxide reacts with acids.

    Na2O + 2HCl 2NaCl + H2O

    MgO + 2HCl MgCl2 + H2O [2 m]Amphoteric oxide reacts with both acids and alkalis.

    Al2O3 + 6HCl 2 AlCl3 + 3H2O

    Al2O3 + 2NaOH 2 NaAlO2 + H2O [2 m]Acidic oxide reacts with alkalis.

    SiO2 + 2NaOH Na2SiO3 + H2O

    SO2 + 2NaOH Na2SO3 + H2OSO3 + 2NaOH Na2SO4 + H2O [2 m]

    (b) (i) They have variable oxidation states [1 m]

    They form complex ions. [1 m]

    They form compounds or ions that are coloured. [1 m]Transition metals and compounds are used as catalysts in industry. [1 m]

    (ii) Transition metals have higher melting points and harder than alkali metals

    due to stronger metallic bonds. [2 m]

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    They have higher densities than alkali metals as the mass of transition metals

    are bigger. [1 m]They are less reactive than alkali metals as tendency to lose electrons to achieve

    stable configuration is lower. [1 m]

    8.

    (a) 2.8.8

    (b) They have stable electronic configuration as their valence shells are full. Hence,they cannot accept, donate or share electrons with other elements.

    (c) Very small amount of energy is needed to overcome the weak Van der Waals' forces

    of attractions between the atoms of the gases.(d) To fill weather balloons.

    To mix with oxygen in gas tanks used for scuba diving.

    (e) No, because they do not contain any free ions or electrons to carry charge.

    9.

    (a) Element Proton number Electron arrangement

    Hydrogen 1 1Carbon 6 2.4

    Nitrogen 7 2.5

    Oxygen 8 2.6

    Chlorine 17 2.8.7

    (b) Through sharing of electrons by atoms so as to achieve octet electron arrangement.

    (c) (i) Hydrogen

    (ii) Oxygen(iii) Nitrogen

    (d)

    (e) (i) Water, H2O(ii) It has a low melting point.

    10. (a) Atoms of noble gases have stable electronic configuration as their valence shell is

    completely filled with electrons. [1 m]

    Hence, they do not donate, accept or share electrons with other atoms. [1 m]

    (b) Group 1 elements have similar chemical properties as they all have the one valenceelectron in the outermost shell. [1 m]

    The reactivity increases as the proton number increases because as the [1 m]

    atomic radius increases, i.e. the valence electron is further from the nucleus.As a result, forces of attraction between the valence electron and the [1 m]

    nucleus is weaker and it is easier to lose the valence electrons to form the stable

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    configuration. [1 m]

    (c) Since the electrons are added to the same shell, the number of shells does [1m]not increase. Hence, increasing number of protons exerts stronger [1 m]

    electrostatic attraction on the electrons and pulls them closer to the nucleus. [2 m]

    As a result, atomic size decreases. [1 m](d) The proton number increases across the Periodic Table, i.e. the nuclear charge

    increases. [1 m]

    But all the valence electrons are placed in the same shell. [1 m]Hence the forces of attraction between the nucleus and the valence electrons are

    increasingly stronger, resulting in a decrease in atomic radius. [3 m]

    (e) (i) 1 [1 m](ii) Rubidium reacts vigorously with cold water, catching fire and even exploding.

    [1 m]

    (iii) 2Rb(s) + 2H2O(l) 2RbOH(aq) + H2(g) [1 m]