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Hydrogen and Alkali Metals

Characteristics of group 1 of the regular table.

You are watching: Number of valence electrons in alkali metals

· determine theelementsin group 1 of the routine table.

· define why team 1elementsare really reactive.

· List various other properties of alkalimetals.

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You probably think ofwateras a substance that have the right to put out fires. However someelementsare therefore reactive that they burn in water. In fact, they essentially explode in water. That’s what is continue in the photo above. About 3 pounds of sodium were included to water, and the an outcome was this explosive reaction. Why is salt such a reactive element? In this lesson girlfriend will find out.

The an initial Group

Sodium (Na) is an facet in group 1 of the routine table of the elements. This group (column) of the table is presented below. It has the nonmetal hydrogen (H) and also sixmetalsthat space calledalkali metals. Elements in the same team of the regular table have the same number of valenceelectrons. These space the electron in their outerenergy levelthat have the right to be affiliated in chemistry reactions. Valence electron determine plenty of of the properties of an element, so aspects in the same team have comparable properties. All the aspects in group 1 have just one valence electron. This makes them very reactive.

Q:Why does having just one valence electron make team 1 elements an extremely reactive?

A:With just one valence electron, team 1 aspects are “eager” to shed that electron. Law so permits them to attain a full outerenergy leveland preferably stability.

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Reactivity of group 1 Elements

Hydrogen is a really reactive gas, and the alkalimetalsare even more reactive. In fact, they space the most reactive steels and, in addition to the elements in team 17, are the most reactive of all elements. The reactivity that alkali metals boosts from the peak to the bottom the the group, therefore lithium (Li) is the the very least reactive alkali metal and also francium (Fr) is the many reactive. Because alkali metals are so reactive, lock are discovered in nature only in mix with other elements. Castle often combine with team 17 elements, i beg your pardon are very “eager” to get an electron. In ~ the URL below, you have the right to watch a video clip that shows just exactly how reactive the alkali steels are.

http://youtu.be/uixxJtJPVXk(2:22)

Other properties of Alkali Metals

Besides being really reactive, alkali metals share a number of other properties.

· Alkali steels are allsolidsat roomtemperature.

· Alkali metals are short in density, and also some of them float onwater.

· Alkali steels are fairly soft. Part are even soft sufficient to reduced with a knife, prefer the salt pictured in theFigurebelow.

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A Closer Look

Although all group 1 aspects share specific properties, such together being very reactive, they room not alike in every way. Three different group 1 aspects are described in an ext detail listed below (Figuresbelow,below, andbelow). An alert the means in i beg your pardon they different from one another.

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Hydrogen has the smallest, lightest atoms of all elements. Pure hydrogen is a colorless, odorless, tasteless gas that is nontoxic however highly flammable. Hydrogen gas exists mostly as diatomic (“two-atom”) molecules (H2), as displayed in the diagram on the right. Hydrogen is the most abundant facet in the universe and the 3rd most abundant aspect on Earth, occurring mainly in link such as water.


Q:Why do you think hydrogen gas commonly exists as diatomic molecules?

A:Each hydrogen atom has just one electron. When two hydrogenatomsbond together, lock share a pair ofelectrons. The mutual electrons fill their onlyenergy level, giving them the many stable arrangement of electrons.

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Potassium is a soft, silvery steel that ignites explosively in water. It conveniently loses that one valence electron to kind positive potassium ions (K+), which are essential by every living cells. Potassium is so important for plants the it is uncovered in almost all fertilizers, like the one shown here. Potassium is plentiful in Earth’s late in mineral such together feldspar.


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Francium has one the the largest, heaviest atoms of all elements. Its one valence electron is far removed from the nucleus, as you deserve to see in the atomic model on the right, so that is quickly removed native the atom. Francium is radioactive and also quickly decays to kind other aspects such together radium. This is why francium is incredibly rare in nature. Much less than an ounce of francium is existing on planet at any given time.


Q:Francium decays too conveniently to formcompoundswith various other elements. Which facets to friend think it would bond with if it could?

A:With one valence electron, francium would certainly bond through a halogen facet in group 17, which has seven valenceelectronsand demands one more to fill its outer energy level. Facets in group 17 encompass fluorine and also chlorine.

Summary

· team 1 that the routine table contains hydrogen and also the alkali metals.

· due to the fact that they have actually just one valence electron, team 1 elements are very reactive. As a result, castle are uncovered in nature only in mix with various other elements.

· Alkali steels are allsolidsat roomtemperature. They are relatively soft and also low in density.

· from the peak to the bottom of team 1, the aspects have heavier, an ext reactiveatoms.

Explore More

At the adhering to URL, click “Group 1 data and also graphs.” use the data in the team 1 table to to fill in the blanks listed below with eitherincreasesordecreases.

http://www.docbrown.info/page07/sblock.htm

From the peak to the bottom of team 1, nature of the alkali metals adjust as follows:

1. Melting allude __________.

2. Boiling suggest __________.

3. Thickness __________.

4. Atomic radius __________.

5. Number of electrons __________.

Review

1. What space alkali metals?

2. Why is hydrogen, a nonmetal, inserted in the same group as the alkali metals?

3. Explain why group 1 elements often formcompoundswith facets in team 17.

4. Compare and also contrast hydrogen and francium.

Alkaline earth Metals

Characteristics of group 2 the the regular table.

· determine alkaline Earthmetals.

· perform properties the alkaline Earthmetals.

· describe why alkaline Earthmetalsare very reactive.

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Sparklers prefer the one this girl is holding make festive enhancements to plenty of celebrations. You may use lock yourself. However watch the end if girlfriend do due to the fact that their flames space really hot! The glowing white flames are developed when magnesium burns. Magnesium is a light- weight metal that burns at a very hightemperature. Other offers of magnesium encompass flash photography, flares, and fireworks. Magnesium is a steel in group 2 of the regular table, which you will certainly read around in this concept.  

The second Group

Barium (Ba) is among sixelementsin team 2 that the periodic table, i m sorry is shown below. Aspects in this team are calledalkaline planet metals. These steels are silver or gray incolor. Lock are reasonably soft and also low in density, although not as soft and lightweight together alkali metals. You deserve to watch a brief video introduction to the alkaline earth metals at this URL:http://www.youtube.com/watch?v=DFQPnHkQlZM.

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Reactivity of Alkaline planet Metals

All alkaline earth metals have similar properties since they all have two valenceelectrons. Lock readily provide up their 2 valence electrons to attain a full outerenergy level, i beg your pardon is the most stable setup of electrons. Together a result, they are very reactive, back not rather as reactive as the alkali metals in team 1. For example, alkaline planet metals will react through coldwater, however not explosively as alkali steels do. Due to the fact that of their reactivity, alkaline planet metals never ever exist as puresubstancesin nature. Instead, castle are constantly found linked with otherelements.

The reactivity of alkaline earth metals rises from the peak to the bottom of the group. That’s due to the fact that theatomsget bigger from the height to the bottom, for this reason the valenceelectronsare farther native the nucleus. Once valence electrons room farther indigenous the nucleus, they space attracted much less strongly by the nucleus and more easily eliminated from the atom. This renders the atom an ext reactive.

Q:Alkali metals have just one valence electron. Why are alkaline earth metals less reactive 보다 alkali metals?

A:It takes an ext energy to remove two valenceelectronsfrom an atom than one valence electron. This provides alkaline earth metals with their 2 valence electrons less reactive than alkali steels with their one valence electron.

Examples the Alkaline earth Metals

For a better understanding of alkaline planet metals, let’s take it a closer look at 2 of them: calcium (Ca) and strontium (Sr). Calcium is a soft, gray, nontoxic alkaline planet metal. Although pure calcium doesn’t exist in nature, calciumcompoundsare an extremely common in Earth’s crust and also in seawater. Calcium is additionally the many abundant steel in the human body, arising as calcium compound such as calcium phosphate and also calcium carbonate. This calcium compounds are discovered in bones and make castle hard and also strong. The skeleton that the median adult contains about a kilogram that calcium. Because calcium—like barium—absorbs x-rays, bones display up white in x-ray images. Calcium is vital component the a healthy and balanced human diet. Great food sources of calcium space pictured inFigurebelow.

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Q:What health troubles might result from a diet low in calcium?

A:Children that don’t get enough calcium while your bones are developing may build a deficiency disease called rickets, in which their bones are softer 보다 normal and also become bent and also stunted. Adults who don’t get enough calcium may develop a condition called osteoporosis, in i m sorry the bones lose calcium and also become weak and brittle. World with osteoporosis are at high danger of bone fractures.

Strontium is a silver-colored alkaline earth metal that is even softer 보다 calcium. Strontiumcompoundsare fairly common and also have a variety of uses—from fireworks come cement come toothpaste. In fireworks, strontium compounds develop deep red explosions. In toothpaste, prefer the one pictured in theFigurebelow, the compound strontium chloride reduces this sensitivity.

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Summary

· elements in group 2 of the routine table are referred to as alkaline earth metals. They are silvery or gray incolor. They are also fairly soft and also low in density.

· Alkaline earth metals are really reactive due to the fact that they readily provide up their 2 valence electron to accomplish a full outerenergy level, which is the most stable setup of electrons. Reactivity boosts from the top to the bottom of the group.

· examples of alkaline earth metals include calcium, which is required for solid bones, and strontium, i beg your pardon is provided for make cement and other products.

Explore More

At the following URL, observe exactly how four various alkaline earth metals react withwater. After ~ you clock the video, prize the inquiries below.

http://www.youtube.com/watch?v=B2ZPrg9IVEo(0:16)

1. Watch the reactions in the video, and also then location the alkaline earth metals from many to least reactive through water.

2. What describes the distinctions in reactivity?

3. Predict the reactivity the beryllium with water. Whereby would it fit in your ranking?

4. Whatsubstancesare produced in every reaction that you it was observed in the video?

Review

1. What room alkaline earth metals? What space their physics properties?

2. Why space alkaline earth metals very reactive?

3. Compare and contrast the reactivity that beryllium (Be) and barium (Ba).

Noble Gases

Characteristics of group 18 that the periodic table.

· determine the noblegases.

· list properties of noblegases.

· define the nonreactivity of noblegasesand just how it is pertained to theoctet rule.

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Okay, helium balloons are light, yet they’re not that light! This fanciful photo serves to make the allude that helium is among the lightestelements. Helium belongs come a team of elements called the noble gases.

What are Noble Gases?

Noble gasesare nonreactive, nonmetallicelementsin team 18 the the periodic table. As you deserve to see in the periodic table inFigurebelow, noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and also radon (Rn). Every noble gases space colorless and also odorless. They likewise have lowboilingpoints, explaining why they space gases at roomtemperature. Radon, in ~ the bottom that the group, is radioactive, so the constantly decays to otherelements. For terrific overview of the noble gases, clock the video at this URL:

http://www.youtube.com/watch?v=jdzBRmLsUM8(4:53)

· come learn just how the noble gases to be discovered, go to this URL:http://www.youtube.com/watch?v=ceQMs30D16E.

· come explore details noble gases, click their symbols in the routine table at this URL:http://www.ptable.com/.

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Q:Based ~ above their position in the routine table (Figureabove), how plenty of valenceelectronsdo you think noble gases have?

A:The number of valenceelectronsstarts at one for aspects in team 1. It then boosts by one native left come right throughout each period (row) that the periodic table for groups 1–2 and 13–18. Therefore, noble gases have eight valence electrons.

Chemical nature of Noble Gases

Noble gases room the the very least reactive that all recognized elements. That’s since with eight valenceelectrons, their outer power levels room full. The only exception is helium, which has just 2 electrons. However helium additionally has a complete outerenergy level, because its only energy level (energy level 1) can hold a maximum of 2 electrons. A complete outer energy level is the many stable arrangement of electrons. Together a result, noble gases cannot become more stable by reaction with various other elements and gaining or losing valence electrons. Therefore, noble gases space rarely affiliated inchemical reactionsand almost never formcompoundswith various other elements.

Noble Gases and theOctet Rule

Because the noble gases are the least reactive of every elements, their eight valence electron are supplied as the traditional for nonreactivity and to explain how other aspects interact. This is proclaimed as the octet (“group of eight”) rule. According to this rule,atomsreact come formcompoundsthat allow them to have actually a team of eight valence electrons choose the noble gases. Because that example, sodium (with one valence electron) reacts v chlorine (with 7 valence electrons) to kind the steady compound sodium chloride (table salt). In this reaction, salt donates an electron and chlorine accepts it, providing each facet an octet the valence electrons.

Some offers of Noble Gases

Did you ever get helium balloons prefer those in the opening picture? uneven a balloon filled through air, a balloon filled v helium demands to it is in weighted down so the won’t float away — although friend don’t have to use one elephant!.

Q:Why walk a helium balloon float away if it’s not weighted down?

A:Heliumatomshave just twoprotons, twoneutrons, and also two electrons, for this reason they have actually less mass than any other atoms other than hydrogen. Together a result, helium is lighter than air, explaining why a helium balloon floats up into the air unless weighted down.

Early incandescent irradiate bulbs, choose the one pictured in theFigurebelow, didn’t last an extremely long. The filaments quickly shed out. Back air was pumped the end of the bulb, it wasn’t a complete vacuum. Oxygen in the tiny amount that air remaining inside the light bulb reacted through the steel filament. This corroded the filament and caused dark shop on the glass. Pour it until it is full a light bulb with argon gas stays clear of these problems. That’s why modern light bulbs are filled through argon.

Q:How go argon avoid the problems of at an early stage light bulbs?

A:As a noble gas with eight electrons, argon doesn’t react with the steel in the filament. This protects the filament and also keeps the glass blub totally free of deposits.

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Noble gases are also used to fill the glass tube of lighted signs like the one in theFigurebelow. Although noble gases space chemically nonreactive, your electrons can be energized by sending out anelectric currentthrough them. As soon as this happens, the electrons jump to a higherenergy level. When the electrons return to their original energy level, they give off energy as light. Different noble gases give off light of different colors. Neon offers off reddish-orange light, like the indigenous “Open” in the sign below. Krypton provides off violet light and xenon provides off blue light.

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Summary

· Noble gases space nonreactive, nonmetallic facets in group 18 that the periodic table.

· Noble gases room the least reactive of all elements. That’s because they have eight valence electrons, which to fill their outerenergy level. This is the most stable arrangement of electrons, for this reason noble gases seldom react with various other elements and formcompounds.

· Theoctet rulestates thatatomsreact to kind compounds that enable them to have actually eight valence electrons choose the noble gases, which space the least reactive elements.

· Noble gases are supplied for balloons, irradiate bulbs, and also lighted signs.

Explore More

Watch the video about noble gases in ~ the complying with URL, and also then price the inquiries below.

http://www.open.edu/openlearn/science-maths-technology/science/chemistry/noble-gases

1. Compare and contrast the reactivity of the elements helium, neon, argon, krypton, and xenon.

2. To compare the thickness of this noble gases come the density of air.

3. Describe how the massive of noble gases alters from the top to the bottom of group 18.

Review

1. What room noble gases?

2. Describe why noble gases room almost totally nonreactive.

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3. What is the octet rule? how is it related to noble gases?

4. Hydrogen (H) atoms have actually one electron and also exist together diatomic (“two-atom”) molecule (H2). Helium atoms have actually two electrons and also exist just as single helium atoms. Describe why hydrogen and helium differ in this way.