Shapes-and-dot-cross-OCR-1 - Chemistry Tuition

Oct 26, 2026

Chemistry tuition questions focus on using dot-and-cross diagrams to explain bonding, molecular shapes, and bond angles in several species. Topics include covalent bonding in ammonia and ammonium chloride, ionic bonding and electron configuration for chloride ions, shapes and bond angles for NH3, NH4+, and ozone, and reasoning about bonding models. Additional tasks cover drawing diagrams for GaCl4− and carbon monoxide with a triple bond and a dative covalent bond.

LanguageEnglish

CategoryExam

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Pages33

Reading Time1 h 23 min

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Dalton Chemistry Tuition

Covalent bonding and molecular shape

Ammonia (NH3) questions

Ammonium chloride (NH4Cl) and ions

Gallium anion (GaCl4−)

Ozone representation

Hydronium ion (H3O+) bonding comparison

Barium chloride and testing sulfate ions

Carbon monoxide and nitric acid diagrams

Bond angles: ammonia vs water

DALTON CHEMISTRY TUITION Chemists have developed models for bonding and structure which are used to explain differentproperties. (a)Ammonia,NH₃,is a covalent compound. (i)Explain what is meant by a covalent bond.……………… … ……… ……… …[1] (ii)Draw a'dot-and-cross diagram to show the bonding in NH₃Show outer electrons only. [1] (ii)Name the shape of the ammonia molecule. Explain,using your 'dot-and-cross'diagram,why ammonia has this shape and has abond angle of 107°. shape:…… … … … …explanation:…… …… … …… …… ……… ………… … ……… ……………………… …… … ………… … ……………………………………………………………………………………………………………………………………------- --- ---- - ---- - --- - ----- ---- - ----- --------… … … … … ………… …… …… ……… ……… …[3] 1………o Ammonia reacts with hydrogen chloride, HCI, to form ammonium chloride,NH₄CL NH₄Clis an ionic compound containing NH₄+and CI- ions. (i) Complete the electron configuration of the Cl- ion. 1s²…………………………………………………………………………………………………………………………………………………………………[1] (ii) Draw a'dot-and-cross diagram to show the bonding in NH₄. Show outer electrons only. iii) State the shape of, and bond angle in, an NH₄+ion. shape:………………………………………………………………………………………………………………………………………………………………… bond angle:………………………………………………………………………………………………………………………………………………………[2] DALTON CHEMISTRY TUITION Gallium forms an anion with chlorine,GaCl₄-.This is thought to have covalent bonds betweena gallium atom and three chlorine atoms and a dative covalent bond from a chloride ion to thegallium atom. (i)Draw a'dot-and-cross'diagram of GaC1₄- (ii)Name the shape of GaC4-.…………………………………… ………………………………………… ………………[1] # DALTON CHEMISTRY TUITION (d)Ozone can be represented by the 'dot-and-cross'diagram shown below. Give the shape of the molecule and bond angle around the central O atom. Explain your answer. …… … [4] When one molecule of a hydrogen halide dissolves in water,a reaction occurs thatforms an ion with the formula H₃O+One of the bonds in this ion is formed in a different way from the other two bonds. Draw a diagram of the ion,showing the two different ways of representing thebonds. Compare the two different ways in which the H-O bonds in this ion are formed. [4 marks] Diagram Comparison DALTON CHEMISTRY TUITION (b)Solid barium chloride has a high melting point.Barium chloride dissolves in water to form a solutionthat can be used to test for sulfate ions. (i)Draw a'dot-and-cross'diagram to show the bonding in solid barium chloride.Show outer electrons only. Carbon monoxide contains a triple bond,and includes a dative covalent bond. Construct a'dot-and-cross'diagram to show the outer electron pairs in a molecule ofcarbon monoxide. (c)Complete the dot-and-cross diagram for the bonding in nitric acid,showing onlyouter shell electrons. Use ()for the oxygen electrons, (X)for the nitrogen electrons and(*)for the hydrogen electron. (3) (a)The diagram shows bond angles in ammonia and water. Explain why the bond angle in water is less than the bond angle in ammonia. (2)------------ --------- -- --- -.--.---- .---- - - -.--- -----.-.-- -- ----.-- ------- -----.----- --

FAQs

What is meant by a covalent bond in these Dalton chemistry questions?

A covalent bond is described as bonding formed by sharing electrons between atoms, rather than electron transfer to form ions.

How do you use dot-and-cross diagrams for ammonia and ammonium ions?

For NH3 and NH4+ you draw outer electrons only and represent how the valence electrons are shared or arranged, then use the diagram to justify molecular shape and bond angles.

What bonding features are highlighted for ozone and carbon monoxide?

Ozone is represented by a dot-and-cross diagram and requires the shape and bond angles around the central oxygen. Carbon monoxide is noted to contain a triple bond and also includes a dative covalent bond.

Oct 26, 2026

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