periodicity

Explain why the ionic radius of chlorine is less than that of sulfur

(chlorine has) an extra proton/more protons/greater nuclear charge/ 17+ compared to 16+; outer electrons attracted more strongly

explain why the other non-metal elements of period 3 have low melting points.

(simple) molecular substances; weak van der Waals'/dispersion/London forces between molecules

An atom of an element contains 19 electrons. In which group of the periodic table does it occur?

1

Which factors lead to an element having a low value of first ionization energy? I. large atomic radius II. high number of occupied energy levels III. high nuclear charge

1 and 2 only

Which of the following properties of the halogens increase from F to I? I. Atomic radius II. Melting point III. Electronegativity

1 and 2 only

explain why Mg has a higher melting point than Na

Mg has greater nuclear charge/greater charge on cation/more valence e/greater number of delocalized electrons/Na has lesser nuclear charge/lesser charge on cation/less valence e/lesser number of delocalized electrons; stronger attraction between cation and delocalized/ free/valence electrons

explain why magnesium has a higher melting point than sodium

Mg has twice as many/more delocalized electrons (compared to Na); the ionic charge is twice as big/greater in Mg (than Na); (electrostatic) attraction between ions and electrons is much greater

Which equation best represents the first ionization energy of magnesium?

Mg(g) → Mg+(g) + e-

When Na, K, and Mg are arranged in increasing order of atomic radius (smallest first), which order is correct?

Mg, Na, K

State the acid-base properties of the following period 3 oxides. MgO Al2Ǒ P4O6 Write equations to demonstrate the acid-base properties of each compound.

MgO basic oxide/alkali; MgO + 2HCl MgCl2 + H2O/MgO + H2O Mg(OH)2; Al2O3 amphoteric oxide/acidic and basic oxide; Al2O3 + 6HCl 2AlCl3 + 3H2O; Al2O3 + 2OH + 3H2O 2Al(OH)4-/Al2O3 + 2OH 2AlO2- + H2O; P4O6 acidic oxide; P4O6 + 6H2O 4H3PO3

Table 8 of the Data Booklet gives the atomic and ionic radii of elements. State and explain the difference between the atomic and ionic radius of nitrogen.

N3- >N/ionic radius > atomic radius because N3- has more electrons than protons; so the electrons are held less tightly

explain the first ionization energy of sodium is greater than that of potassium.

Na electron closer to nucleus/in lower energy level/Na has less shielding effect

explain the first ionization energy of sodium is less than that of magnesium.

Na has lower nuclear charge/number of protons; electrons being removed are from same energy level/shell; Na has larger radius/electron further from nucleus

Discuss the acid-base nature of the period 3 oxides. Write an equation to illustrate the reaction of one of these oxides to produce an acid, and another equation of another of these oxides to produce a hydroxide

Na, Mg are basic Al is amphoteric Si, P, S and Cl are acidic SO2 + H2O - H2SO3/SO3 + H2O H2SO4

Describe the acid-base character of the oxides of the period 3 elements Na to Ar. For sodium oxide and sulfur trioxide, write balanced equations to illustrate their acid-base character.

Na, Mg: basic; Al: amphoteric; Si to Cl: acidic; Ar: no oxide; NaO + H2O 2NaOH; SǑ + H2O H2SÒ4

Write an equation for each reaction between water and (i) sodium oxide ................................................................................................ ................................................................................................ (1) (ii) sulfur dioxide.

Na2O + H2O → 2Na+ + 2OH-; SO2 + H2O → H2SO3

Which compound of an element in period 3 reacts with water to form a solution with a pH greater than 7? A. SiÓ B. SiCl4 C. NaCl D. NáO

NáO

Describe the acid-base character of the oxides of the period 3 elements Na to Ar. For sodium oxide and sulfur trioxide, write balanced equations to illustrate their acid-base character

Oxides of: Na and Mg are basic; Al is amphoteric; Si to Cl are acidic; Ar has no oxide Na2O + H2O - 2NaOH and SO3 + H2O - H2SO4

explain why there is a large increase in ionic radius from silicon to phosphorus.

P3- has one more shell than Si4+; some justification in terms of electron loss/gain; net attractive forces

Which statement is correct for all elements in the same period?

They have the same number of occupied energy levels

Distinguish between the terms period and group.

period is a horizontal row in the periodic table and a group is a vertical column

Explain why the electronegativity of phosphorus is greater than that of aluminium.

phosphorus has a higher (effective) nuclear charge; radius of P is smaller; electron pair/bonding electrons attracted more strongly

Which property increases down group 1?

reactivity

explain why the ionic radius of Na+ is less than that of F-.

same electron arrangement/both have two complete shells; extra protons in Na+ (attract the electrons more strongly)

Suggest why much more energy is needed to remove an electron from Na+ than from Mg+.

second electron in Na removed from n = 2, whereas second electron in Mg removed from n = 3

Which change explains why the boiling points of the halogens increase as their molecular masses increase?

The intermolecular attraction due to temporarily induced dipoles increases

Which properties of the alkali metals decrease going down group 1?

First ionization energy and melting point

Explain, in terms of its structure and bonding, why silicon dioxide, SiÓ, has a high melting point.

silicon dioxide is macromolecular/giant covalent; many/strong covalent bonds must be broken

Explain why sulfur has a lower first ionization energy than oxygen, and also a lower first ionization energy than phosphorus.

IES < IEO: valence electron in S in n = 3, in O in n = 2/e further away/S has another electron shell/atomic radius of S greater than that of O; less attracted to nucleus/experiences greater screening from inner electrons IES < IEP: electron removed from S is paired; greater repulsion due to two electrons in the same (p) orbital/paired electrons in S

Describe three similarities and one difference in the reactions of lithium and potassium with water.

similarities: bubbles are produced, solution becomes alkaline/basic, solution gets hot

Which statement is correct for the halogen group?

Iodide ions can be oxidized to iodine by chlorine

A potassium atom has a larger atomic radius than a sodium atom. Which statement about potassium correctly explains this difference?

It has more energy levels occupied by electrons.

Which pair of elements reacts most readily? A. Li + Br2 B. Li + Cl2 C. K + Br2 D. K + Cl2

K + Cl2

Which pair would react together most vigorously? A. Li and Cl2 B. Li and Br2 C. K and Cl2 D. K and Br2

K and Cl2

Explain how the first ionization energy of K compares with that of Na and Ar.

K less than Na and Ar because electron removed (from K) is from higher energy level/further from nucleus/in n = 4 compared to n = 3

When the following species are arranged in order of increasing radius, what is the correct order? A. Cl-, Ar, K+ B. K+, Ar , Cl- C. Cl-, K+, Ar D. Ar, Cl-, K+

K+, Ar , Cl-

Which statement is correct for a periodic trend? A. Ionization energy increases from Li to Cs. B. Melting point increases from Li to Cs. C. Ionization energy increases from F to I. D. Melting point increases from F to I.

Melting point increases from F to I.

Which statement about electronegativity is correct?

Metals generally have lower electronegativity values than non-metals.

Explain the difference between the first ionization energies of Na and Mg.

Mg greater than Na because (Mg has) greater nuclear charge/one more proton/12 protons compare to 11; electron removed is in same (main) higher energy level/shell; smaller (atomic) radius; so more strongly attracted by nucleus;

Which of the following statements are correct? I. The melting points decrease from Li Cs for the alkali metals. II. The melting points increase from F I for the halogens. III. The melting points decrease from Na Ar for the period 3 elements

1 and 2 only

Which properties are typical of most non-metals in period 3 (Na to Ar)? I. They form ions by gaining one or more electrons. II. They are poor conductors of heat and electricity. III. They have high melting points.

1 and 2 only

Which statements about period 3 are correct? I. The electronegativity of the elements increases across period 3. II. The atomic radii of the elements decreases across period 3. III. The oxides of the elements change from acidic to basic across period 3.

1 and 2 only

Which statements about the periodic table are correct? I. The elements Mg, Ca and Sr have similar chemical properties. II. Elements in the same period have the same number of main energy levels. III. The oxides of Na, Mg and P are basic.

1 and 2 only

Which oxides produce an acidic solution when added to water? I. P4Ō0 II. MgO III. SǑ

1 and 3 only

Which properties of period 3 elements increase from sodium to argon? I. Nuclear charge II. Atomic radius III. Electronegativity

1 and 3 only

Which of the reactions below occur as written? I. Br2 + 2I- → 2Br- + I2 II. Br2 + 2Cl- → 2Br- + Cl2

1 only

What happens when sodium is added to water? I. A gas is evolved II. The temperature of the water increases III. A clear, colourless solution is formed

1, 2, and 3

How many protons, neutrons and electrons are present in each atom of 31P?

15 16 15

Which general trends are correct for the oxides of the period 3 elements (NáO to Cl2O)? I. Acid character decreases. II. Electrical conductivity (in the molten state) decreases. III. Bonding changes from ionic to covalent.

2 and 3 only

Which oxides produce an acidic solution when added to water? I. SiÓ II. P4O6 III. SÓ

2 and 3 only

Which statements about the periodic table are correct? I. Elements in period 3 have similar chemical properties. II. Elements in group 7 show a gradual change in physical properties. III. The position of an element in period 3 is related to the number of electrons in the highest occupied energy level.

2 and 3 only

Which of the physical properties below decrease with increasing atomic number for both the alkali metals and the halogens? I. Atomic radius II. Ionization energy III. Melting point

2 only

State the electron arrangement of nitrogen and explain why it is found in period 2 and group 5 of the periodic table.

2,5; electrons in two energy levels/shells; five outer/valence electrons;

Lithium reacts with water. Write an equation for the reaction and state two observations that could be made during the reaction.

2Li + 2H2O - 2LiOH + H2; bubbles and heat are produced

Give an equation for one of these reactions- lithium and potassium with water. Suggest a pH value for the resulting solution, and give a reason for your answer.

2Li + 2H2O → 2Li+ + 2OH- + H2 pH greater than or equal to 11; LiOH/KOH is a strong base/strong alkali/high concentration of OH-

Write an equation for the reaction of lithium with water.

2Li(s) + 2H2O(1) - 2LiOH(aq) + H2(g)

An element is in group 4 and period 3 of the periodic table. How many electrons are in the highest occupied energy level of an atom of this element?

4

For which element are the group number and the period number the same? A. Li B. Be C. B D. Mg

Be

Which ion has the largest radius? A. Cl- B. K+ C. Br- D. F-

Br-

Explain why Cl2 rather than Br2 would react more vigorously with a solution of I-.

Cl2 is a stronger oxidizing agent/Chlorine's outer shell closer to nucleus; Cl2 has greater attraction for electrons/has a higher electron affinity

Explain why Cl2 rather than Br2 would react more vigorously with a solution of I-.

Cl2 stronger oxidising agent; Cl2 has greater attraction for electrons/has a higher electron affinity

Which statement about the elements in group 7 is correct?

Cl2 will oxidize I-.

Which element is a transition metal? A. Ca B. Cr C. Ge D. Se

Cr

Which pair of elements has the greatest difference in electronegativity? A. Cs and F B. Cs and Cl C. Cs and Br D. Cs and I

Cs and F

Which series is arranged in order of increasing radius?

Cá+ < K+ < Cl-

Which series is arranged in order of increasing radius? A. Cá+ < Cl- < K+ B. K+ < Cá+ < Cl- C. Cá+ < K+ < Cl- D. Cl- < K+ < Cá+

Cá+ < K+ < Cl-

Which is the best definition of electronegativity?

Electronegativity is the attraction of an atom for a bonding pair of electrons.

Which equation represents the first ionization energy of fluorine?

F(g) - F+(g) + e-

Which statement describes the trends of electronegativity values in the periodic table?

Values increase from left to right across a period and decrease down a group

Explain what is meant by the term electronegativity and explain why the electronegativity of chlorine is greater than that of bromine.

ability of atom to attract bonding pair of electrons/electrons in a covalent bond; chlorine has a smaller radius/(electrons) closer to nucleus/in lower energy level; repelled by fewer inner electrons/decreased shielding effect

Table 6 of the Data Booklet lists melting points of the elements. Explain the trend in the melting points of the alkali metals, halogens and period 3 elements.

alkali metals: metallic bonding/a bed of cations in a sea of electrons; as radius increases down the group, valence electrons are further away from nucleus (and strength of metallic bonding decreases); halogens: non-polar/van der Waals' forces between molecules; as size increases van der Waals' forces increase (and melting point increases); period 3 elements: increase in melting points of metals (Na, Mg, Al) due to increase in number of valence electrons and decrease in size/the way atoms are packed as solids; increased number of delocalized or valence electrons

Classify each of the following oxides as acidic, basic or amphoteric. (i) aluminium oxide ................................................................................................ (1) (ii) sodium oxide ................................................................................................ (1) (iii) sulfur dioxide

amphoteric, basic, acidic

Which property generally decreases across period 3?

atomic radius

State and explain the trends in the atomic radius and the ionization energy for the period 3 elements Na to Cl.

atomic radius decreases; because nuclear charge increases and electrons are added to same main (outer) energy level; ionization energy increases; because nuclear charge increases and the electron removed is closer to the nucleus/is in the same energy level

State and explain the trends in the atomic radius and the ionization energy for the alkali metals Li to Cs.

atomic radius increases; because more full energy levels are used or occupied/outer electrons further from nucleus/outer electrons in a higher shell; ionization energy decreases; because the electron removed is further from the nucleus/increased repulsion by inner-shell electrons

Table 8 of the Data Booklet gives the atomic and ionic radii of elements. State and explain the difference between the atomic radius of nitrogen and oxygen.

atomic radius of N > O because O has greater nuclear charge; greater attraction for the outer electrons

Table 8 of the Data Booklet gives the atomic and ionic radii of elements. State and explain the difference between the atomic radius of nitrogen and phosphorus

atomic radius of P > N because P has outer electrons in an energy level further from the nucleus

The compounds NáO, Al2Ǒ and SÓ respectively are

basic, amphoteric and acidic.

Table 8 in the Data Booklet contains two values for the ionic radius of silicon. Explain, by reference to atomic structure and electron arrangements, why the two values are very different.

both have same number of protons/14 protons/nuclear charge/core charge; Si4+ formed by electron loss, Si4 formed by electron gain; Si4+ : 2.8 arrangement/2 (complete) energy levels/electrons in n = 2; Si4 : 2.8.8 arrangement/3 (complete) energy levels/electrons in n = 3

Which two elements react most vigorously with each other? A. chlorine and lithium B. chlorine and potassium C. iodine and lithium D. iodine and potassium

chlorine and potassium

explain the electronegativity of chlorine is higher than that of sulfur.

chlorine has a higher nuclear charge; attracts the electron pair/electrons in bond more strongly

explain why the first ionization energy of magnesium is lower than that of fluorine.

electron removed from higher energy level/further from nucleus/ greater atomic radius; increased repulsion by extra inner shell electrons/increased shielding effect

Which property decreases down group 7 in the periodic table?

electronegativity

Which property decreases down group 7 in the periodic table? A. atomic radius B. electronegativity C. ionic radius D. melting point

electronegativity

State and explain the trend in electronegativity across period 3 from Na to Cl.

electronegativity increases (along period 3 from Na to Cl); number of protons increases/nuclear charge increase/core charge increase/size of atom decreases

State and explain the trend in electronegativity across period 3 from Na to Cl.

electronegativity increases (along period 3 from Na to Cl); number of protons increases/nuclear charge increases/core charge increases /size of atoms decreases

explain why Si has a very high melting point.

giant/network/lattice/macromolecular structure; many/strong covalent bonds (need to be broken)

The first ionization energies of the elements are shown in Table 7 of the Data Booklet. Explain why the first ionization energy of magnesium is greater than that of sodium.

greater nuclear charge/greater number of protons/atom radius g is smaller; stronger attraction (for electron)

State and explain the trend in the ionization energy of alkali metals down the group.

ionization energy) decreases; radius increases/valence electrons further away from nucleus/ electron removed from higher shell

Which species has the largest radius? A. Cl- B. K C. Na+ D. K+

k

Explain why the magnesium ion is much smaller than the magnesium atom.

loss of 2 electrons/outer electrons; 3 shells to 2; net attractive force increases

Rubidium is an element in the same group of the periodic table as lithium and sodium. It is likely to be a metal which has a

low melting point and reacts vigorously with water.

The x-axis of the graph below represents the atomic number of the elements in period 3. Which variable could represent the y-axis?

melting point

Explain, in terms of their structure and bonding, why the element sulfur is a non-conductor of electricity and aluminium is a good conductor of electricity.

sulfur is (simple) molecular; (contains) covalent bonds/no delocalized electrons/all (outer) electrons used in bonding; aluminium contains positive ions and delocalized electrons; (delocalized) electrons move (when voltage applied or current flows)

State the meaning of the term electronegativity and explain why the noble gases are not assigned electronegativity values.

the ability of an atom to attract a bonding pair of electrons; inert/do not react/do not attract electrons/stable electron configuration/full outer electron shell/do not form bonds

State the meaning of the term electronegativity.

the ability of an element/atom/nucleus to attract a bonding pair of electrons

What increases in equal steps of one from left to right in the periodic table for the elements lithium to neon?

the number of electrons in the atom