# 18.1 Periodicity  (Page 8/16)

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## Chemistry end of chapter exercises

How do alkali metals differ from alkaline earth metals in atomic structure and general properties?

The alkali metals all have a single s electron in their outermost shell. In contrast, the alkaline earth metals have a completed s subshell in their outermost shell. In general, the alkali metals react faster and are more reactive than the corresponding alkaline earth metals in the same period.

Why does the reactivity of the alkali metals decrease from cesium to lithium?

Predict the formulas for the nine compounds that may form when each species in column 1 of [link] reacts with each species in column 2.

1 2
Na I
Sr Se
Al O

$\begin{array}{l}\text{Na}+{\text{I}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{2NaI}\\ \text{2Na}+\text{Se}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{Na}}_{2}\text{Se}\\ \text{2Na}+{\text{O}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{Na}}_{2}{\text{O}}_{2}\end{array}$
$\begin{array}{l}\text{Sr}+{\text{I}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{SrI}}_{2}\\ \text{Sr}+\text{Se}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{SrSe}\\ \text{2Sr}+{\text{O}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{2SrO}\end{array}$
$\begin{array}{l}\text{2Al}+{\text{3I}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{2AlI}}_{3}\\ \text{2Al}+\text{3Se}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{Al}}_{2}{\text{Se}}_{3}\\ \text{4Al}+{\text{3O}}_{2}\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{2Al}}_{2}{\text{O}}_{3}\end{array}$

Predict the best choice in each of the following. You may wish to review the chapter on electronic structure for relevant examples.

(a) the most metallic of the elements Al, Be, and Ba

(b) the most covalent of the compounds NaCl, CaCl 2 , and BeCl 2

(c) the lowest first ionization energy among the elements Rb, K, and Li

(d) the smallest among Al, Al + , and Al 3+

(e) the largest among Cs + , Ba 2+ , and Xe

Sodium chloride and strontium chloride are both white solids. How could you distinguish one from the other?

The possible ways of distinguishing between the two include infrared spectroscopy by comparison of known compounds, a flame test that gives the characteristic yellow color for sodium (strontium has a red flame), or comparison of their solubilities in water. At 20 °C, NaCl dissolves to the extent of $\frac{\text{35.7 g}}{\text{100 mL}}$ compared with $\frac{\text{53.8 g}}{\text{100 mL}}$ for SrCl 2 . Heating to 100 °C provides an easy test, since the solubility of NaCl is $\frac{\text{39.12 g}}{\text{100 mL}},$ but that of SrCl 2 is $\frac{\text{100.8 g}}{\text{100 mL}}.$ Density determination on a solid is sometimes difficult, but there is enough difference (2.165 g/mL NaCl and 3.052 g/mL SrCl 2 ) that this method would be viable and perhaps the easiest and least expensive test to perform.

The reaction of quicklime, CaO, with water produces slaked lime, Ca(OH) 2 , which is widely used in the construction industry to make mortar and plaster. The reaction of quicklime and water is highly exothermic:
$\text{CaO}\left(s\right)+{\text{H}}_{2}\text{O}\left(l\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{Ca}{\left(\text{OH}\right)}_{2}\left(s\right)\phantom{\rule{3em}{0ex}}\text{Δ}H=\text{−350 kJ}\phantom{\rule{0.2em}{0ex}}{\text{mol}}^{\text{−1}}$

(a) What is the enthalpy of reaction per gram of quicklime that reacts?

(b) How much heat, in kilojoules, is associated with the production of 1 ton of slaked lime?

Write a balanced equation for the reaction of elemental strontium with each of the following:

(a) oxygen

(b) hydrogen bromide

(c) hydrogen

(d) phosphorus

(e) water

(a) $\text{2Sr}\left(s\right)+{\text{O}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{2SrO}\left(s\right);$ (b) $\text{Sr}\left(s\right)+\text{2HBr}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{SrBr}}_{2}\left(s\right)+{\text{H}}_{2}\left(g\right);$ (c) $\text{Sr}\left(s\right)+{\text{H}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{SrH}}_{2}\left(s\right);$ (d) $\text{6Sr}\left(s\right)+{\text{P}}_{4}\left(s\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{2Sr}}_{3}{\text{P}}_{2}\left(s\right);$ (e) $\text{Sr}\left(s\right)+{\text{2H}}_{2}\text{O}\left(l\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{Sr}{\left(\text{OH}\right)}_{2}\left(aq\right)+{\text{H}}_{2}\left(g\right)$

How many moles of ionic species are present in 1.0 L of a solution marked 1.0 M mercury(I) nitrate?

What is the mass of fish, in kilograms, that one would have to consume to obtain a fatal dose of mercury, if the fish contains 30 parts per million of mercury by weight? (Assume that all the mercury from the fish ends up as mercury(II) chloride in the body and that a fatal dose is 0.20 g of HgCl 2 .) How many pounds of fish is this?

11 lb

The elements sodium, aluminum, and chlorine are in the same period.

(a) Which has the greatest electronegativity?

(b) Which of the atoms is smallest?

(c) Write the Lewis structure for the simplest covalent compound that can form between aluminum and chlorine.

(d) Will the oxide of each element be acidic, basic, or amphoteric?

Does metallic tin react with HCl?

Yes, tin reacts with hydrochloric acid to produce hydrogen gas.

What is tin pest, also known as tin disease?

Compare the nature of the bonds in PbCl 2 to that of the bonds in PbCl 4 .

In PbCl 2 , the bonding is ionic, as indicated by its melting point of 501 °C. In PbCl 4 , the bonding is covalent, as evidenced by it being an unstable liquid at room temperature.

Is the reaction of rubidium with water more or less vigorous than that of sodium? How does the rate of reaction of magnesium compare?

#### Questions & Answers

hydrogen is a monovalent why aluminum is a divalent
Did you mean trivalent? This is because Aluminium has three electroms orbiting in the valence (furthest shell) which are involved in covalent bonding where each electron becomes a pair with another one in the other non metal and make a single bond. N. B: each single covalent bond contains 2 electr
Abdelkarim
Electrons, one from each atom. Did you know that god said '' And, [O Muhammad], you are not [engaged] in any matter or recite any of the Qur'an and you [people] do not do any deed except that We are witness over you when you are involved in it. And not absent from your Lord is any [part] of an atom
Abdelkarim
... atom's weight within the earth or within the heaven or [anything] smaller than that or greater but that it is in a clear register. ''
Abdelkarim
wat gives perfume it's sweet smell
These are organic compounds, which have plentiful functional groups which react with certain substances through a pathway in the cells lining nostrils which sends impulses that make you sense its sweet. Did you prophet Muhammad (peace upon him) encourages the use of perfume.
Abdelkarim
what is it use for
amagai
Prophet Muhammad (peace be upon him) used to love cleanliness and good scent. ... It was highlighted, in many hadiths, his love for fragrance and good scent like musk, 'ud and ambergris.
Abdelkarim
the types of giant covalent structure
define the following terms. electrovalent bonding
Nobert
 An unknown noble gas was allowed to flow into a 300.0 mL glass bulb until the P = 685 torr. Initially, the glass bulb weighed 32.50 g, but now it weighs 33.94 g. If the temperature is 27.0 °C, what’s the identity of the gas?
* Use PV=nRT with correct units to find n (number of moles) * Use n = mass/ Ar (Ar is relative atomic mass) Ar = 131.15 -> Xenon N. B: P is in pascals, V in m3, n in mol, R in J/ k. Mol, T in kelvin *Thank God
Abdelkarim
N. B: As it is a noble gas it is mono-atomic so the Ar does not need to be divided by two (not diatomic).
Abdelkarim
what is molecule
molecules are produced by double atom from example this is hydrogen atom and this is hydrogen2 are call that hydrogen molecules or gass
Naldo
What is the generic name for the compound
what is the formular for methane
CH4 , it is the simplest alkane
Abdelkarim
what is the formula for alkaline
Olom
hi
Yusuf
I wish to learn to more of chemistry, can someone please teach me.
Yusuf
what is zero gravity
every object is that zero gravity
Rabiu
Probably when an object is in space and there are no nearby masses that pull her, and exert gravity
Abdelkarim
Alright. .good job
Rabiu
And all majesty to God, (وَهُوَ ٱلَّذِی خَلَقَ ٱلَّیۡلَ وَٱلنَّهَارَ وَٱلشَّمۡسَ وَٱلۡقَمَرَۖ كُلࣱّ فِی فَلَكࣲ یَسۡبَحُونَ) [سورة الأنبياء 33 And it is He who created the night and the day and the sun and the moon; all [heavenly bodies] in an orbit are swimming. General theory of relativity in Qur
Abdelkarim
what is molecule?
Olom
what is lattice energy
why is CO a neutral oxide and CO2 an acidic oxide
Because when CO2 dissolves in water forming a weak acid. CO does not dissolve in water as it has strong triple bond.
Abdelkarim
What is acid
which donate H+ or accept lone pair of electron
Kajal
kinetic theory of matter and gas law
hi
Victoria
pls explain
Victoria
what is clay
material containing clay minerals. Clays develop plasticity when wet, due to a molecular film of water surrounding the clay particles, but become hard, brittle and non–plastic upon drying or firing. Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours
Abdelkarim
due iron oxide. The four types of clay are Earthenware clay, Stoneware clay, Ball clay, and Porcelain. All of them can be used to make pottery, but the end result would differ a lot thanks to their different textures, colors, and flexibilities.
Abdelkarim
And do you know that god has created human from clay (وَلَقَدۡ خَلَقۡنَا ٱلۡإِنسَـٰنَ مِن صَلۡصَـٰلࣲ مِّنۡ حَمَإࣲ مَّسۡنُونࣲ) [سورة الحجر 26] And We did certainly create man out of clay from an altered black mud. You can install Quran from paly store for free with translations.
Abdelkarim
darw a periodic table
draw a periodic table
Hazard
You will arrange the elements into row and coloumns according to increasing proton number. You may want to use symbols or their names. Hydrogen, Helium, etc. God has created all these elements from nothing, in Islam we know God is the creator.
Abdelkarim
why are you drawing a periodic table? why not just print one from the internet and use as a reference
Jakhari
Great thought
Bright
how are you?
alright , how about you
Marina
am fine
Agbo
your name is Agbo?
Marina
my name is amel
Farid
l use the email of my husband
Farid