# 18.1 Periodicity  (Page 7/16)

 Page 7 / 16

Aluminum is a very good reducing agent and may replace other reducing agents in the isolation of certain metals from their oxides. Although more expensive than reduction by carbon, aluminum is important in the isolation of Mo, W, and Cr from their oxides.

## Group 14

The metallic members of group 14 are tin, lead, and flerovium. Carbon is a typical nonmetal. The remaining elements of the group, silicon and germanium, are examples of semimetals or metalloids. Tin and lead form the stable divalent cations, Sn 2+ and Pb 2+ , with oxidation states two below the group oxidation state of 4+. The stability of this oxidation state is a consequence of the inert pair effect. Tin and lead also form covalent compounds with a formal 4+-oxidation state. For example, SnCl 4 and PbCl 4 are low-boiling covalent liquids.

Tin reacts readily with nonmetals and acids to form tin(II) compounds (indicating that it is more easily oxidized than hydrogen) and with nonmetals to form either tin(II) or tin(IV) compounds (shown in [link] ), depending on the stoichiometry and reaction conditions. Lead is less reactive. It is only slightly easier to oxidize than hydrogen, and oxidation normally requires a hot concentrated acid.

Many of these elements exist as allotropes. Allotropes are two or more forms of the same element in the same physical state with different chemical and physical properties. There are two common allotropes of tin. These allotropes are grey (brittle) tin and white tin. As with other allotropes, the difference between these forms of tin is in the arrangement of the atoms. White tin is stable above 13.2 °C and is malleable like other metals. At low temperatures, gray tin is the more stable form. Gray tin is brittle and tends to break down to a powder. Consequently, articles made of tin will disintegrate in cold weather, particularly if the cold spell is lengthy. The change progresses slowly from the spot of origin, and the gray tin that is first formed catalyzes further change. In a way, this effect is similar to the spread of an infection in a plant or animal body, leading people to call this process tin disease or tin pest.

The principal use of tin is in the coating of steel to form tin plate-sheet iron, which constitutes the tin in tin cans. Important tin alloys are bronze (Cu and Sn) and solder (Sn and Pb). Lead is important in the lead storage batteries in automobiles.

## Group 15

Bismuth , the heaviest member of group 15, is a less reactive metal than the other representative metals. It readily gives up three of its five valence electrons to active nonmetals to form the tri-positive ion, Bi 3+ . It forms compounds with the group oxidation state of 5+ only when treated with strong oxidizing agents. The stability of the 3+-oxidation state is another example of the inert pair effect.

## Key concepts and summary

This section focuses on the periodicity of the representative elements. These are the elements where the electrons are entering the s and p orbitals. The representative elements occur in groups 1, 2, and 12–18. These elements are representative metals, metalloids, and nonmetals. The alkali metals (group 1) are very reactive, readily form ions with a charge of 1+ to form ionic compounds that are usually soluble in water, and react vigorously with water to form hydrogen gas and a basic solution of the metal hydroxide. The outermost electrons of the alkaline earth metals (group 2) are more difficult to remove than the outer electron of the alkali metals, leading to the group 2 metals being less reactive than those in group 1. These elements easily form compounds in which the metals exhibit an oxidation state of 2+. Zinc, cadmium, and mercury (group 12) commonly exhibit the group oxidation state of 2+ (although mercury also exhibits an oxidation state of 1+ in compounds that contain ${\text{Hg}}_{2}{}^{2+}\right).$ Aluminum, gallium, indium, and thallium (group 13) are easier to oxidize than is hydrogen. Aluminum, gallium, and indium occur with an oxidation state 3+ (however, thallium also commonly occurs as the Tl + ion). Tin and lead form stable divalent cations and covalent compounds in which the metals exhibit the 4+-oxidation state.

what is molar mass?
Molar mass is defined as the mass of a sample of a compound divided by the amount of substance of that sample.
Love
atom is the smallest indivisible part of an element that takes place in chemical reaction
An atom is the smallest indivisible part of an element
Vibes
what is chemistry?
what is an atom
Mathias
what is an atom?
Mathias
the hydroxyl group is a functional group consisting of a hydrogen atom covalently bonded to an oxygen atom.
Itz
Names are of homologous series
what's an hydroxyl group?
A hydroxy or hydroxyl group is the entity with the formula OH. It contains oxygen bonded to hydrogen. In organic chemistry, alcohols and carboxylic acids contain hydroxy groups. The anion [OH⁻], called hydroxide, consists of a hydroxyl group.
okwara
what are the steps to follow when writing the condensed formula of elements
What is organic chemistry
what's organic chemistry?
why do electrons have no mass
hello
Samuel
hello there
Oliver
hi and who say electrons has no mass ? it does have but most at time consider negleable
Eyong
hello
Lagazani
Lagazani
yeah i will calculate it
divine
Because it's mass it very very small compare with mass of atom
Yasmeen
it's simple
lola
consider the rxn of butadiene .Butadiene is prepared by the gas phase catalytic dehydrogenation of 1-butene , at 900K and 1 bar. c4H8 (g)_ C4H6 (g) + H2 (g) (a) In order to suppress side reactions , the butane is diluted with steam before it passes into the reactor.Estimate the conversion
Rodrick
Estimate the conversion of 1-butene for a feed consisting of 10 moles of steam per mole of 1-butene. (b) find the conversion if the inerts were absent and side reactions are ignored .
Rodrick
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Rodrick
wat is the difference between electrochemical chemical corrosion
Uzor
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Lagazani
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Sophia pls check on fb u will see transcendence Internationale is a group from here just join over, and ask any question in science from there we here created it
Eyong
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Eyong
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Eyong
for now chemistry is the study of matter and it properties, why and how element combined to form other substances
Eyong
Chemistry is a group that identifies properties of matter and many more
Alona
Wow and chemistry also is the systematic study of nature
Eyong
chemistry is the study of the structure, properties of matter and the effect of addition or removal of heat from substances.
Bra
calculate the relative molecular Mass of the following 1 ZnCl2 2 NaNo3 3 HNO3 4 CaO
2) 23+14+(16×3)= 3)1+14+(16×3)= 4) 40+16= 1) Zn+71= that's how they do it but for Zn I don't know its mass number
Eyong
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Eyong
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Christian
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Gold
radioactivity is the spontaneous disintegration of the nucleus of an atom of an element to emmit radiation
Vivian
When dividing a certain and uncertain number, you still use sig figs? Ex: 12.86g divided by 12 M&Ms
hi pls who n knows organic chemistry
mi too needs help
Christian
i don't understand
Ekene
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Christian
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Alanna
organic chemistry as a whole
Christian
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Christian
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Judith
but am a Ghanaian
Judith
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Judith
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Christian
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Eyong
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Christian
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Judith
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Eyong
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Christian
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Judith
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Christian
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Judith
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Christian
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Judith
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Eyong
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Eyong
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Christian
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Eyong
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Christian
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Eyong
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Judith
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Judith
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Christian
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Judith
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Eyong
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Judith
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Christian
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Judith
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Judith
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Eyong
ueah
Christian
Eyong
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Eyong
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Christian
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Eyong
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Christian
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Christian
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Eyong
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Christian
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Christian
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Judith
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Christian
wat is periodicity of element
Abraham
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Christian
wat is periodicity of element
Abraham
Abraham periodicity is the trend of variation in the property of element in the periodic table with increased in atomic number but is mostly on physical properties
Eyong
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Christian
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Judith
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Christian
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Judith
Tru Daniel
Christian
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Eyong
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Christian
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Eyong
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Justice
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Eyong
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divine
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Eyong