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Hydrogen and Alkali Metals

Characteristics of group 1 the the regular table.

You are watching: How many valence electrons do the alkaline earth metals possess?

· identify theelementsin team 1 the the regular table.

· describe why group 1elementsare an extremely reactive.

· List various other properties the alkalimetals.

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You probably think ofwateras a problem that can put the end fires. But someelementsare for this reason reactive that they burn in water. In fact, they essentially explode in water. That’s what is keep going in the photo above. Around 3 pounds of salt were added to water, and also the an outcome was this explosive reaction. Why is sodium such a reactive element? In this lesson you will find out.

The first Group

Sodium (Na) is an facet in team 1 the the regular table that the elements. This group (column) of the table is displayed below. It has the nonmetal hydrogen (H) and also sixmetalsthat space calledalkali metals. Facets in the same group of the routine table have actually the same number of valenceelectrons. These space the electron in your outerenergy levelthat have the right to be affiliated in chemistry reactions. Valence electrons determine countless of the properties of one element, so elements in the same team have similar 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 group 1 elements very reactive?

A:With simply one valence electron, team 1 elements are “eager” to lose that electron. Doing so permits them to achieve a complete outerenergy leveland best stability.

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Reactivity of team 1 Elements

Hydrogen is a an extremely reactive gas, and the alkalimetalsare even much more reactive. In fact, they room the most reactive steels and, together with the aspects in team 17, room the most reactive of all elements. The reactivity of alkali metals boosts from the peak to the bottom that the group, for this reason lithium (Li) is the least reactive alkali metal and also francium (Fr) is the most reactive. Since alkali steels are so reactive, castle are discovered in nature just in combination with various other elements. They often incorporate with group 17 elements, i beg your pardon are very “eager” to acquire an electron. At the URL below, you have the right to watch a video clip that mirrors just just how reactive the alkali metals are.

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

Other nature of Alkali Metals

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

· Alkali steels are allsolidsat roomtemperature.

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

· Alkali metals are relatively soft. Some are even soft enough to reduced with a knife, favor the sodium pictured in theFigurebelow.

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A Closer Look

Although all team 1 aspects share details properties, such together being an extremely reactive, they space not alike in every way. Three various group 1 aspects are explained in more detail listed below (Figuresbelow,below, andbelow). Notice the ways in i m sorry they different from one another.

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Hydrogen has actually the smallest, lightest atoms of every elements. Pure hydrogen is a colorless, odorless, tasteless gas that is nontoxic yet highly flammable. Hydrogen gas exists greatly 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 element on Earth, arising mainly in compound such together water.


Q:Why carry out you think hydrogen gas normally exists as diatomic molecules?

A:Each hydrogen atom has actually just one electron. As soon as two hydrogenatomsbond together, castle share a pair ofelectrons. The common electrons to fill their onlyenergy level, offering them the many stable setup of electrons.

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Potassium is a soft, silvery metal that ignites explosively in water. It quickly loses the one valence electron to type positive potassium ions (K+), i beg your pardon are essential by all living cells. Potassium is so important for plants the it is uncovered in practically all fertilizers, choose the one shown here. Potassium is plentiful in Earth’s late in minerals such as feldspar.


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Francium has actually one that the largest, heaviest atoms of all elements. Its one valence electron is far removed indigenous the nucleus, as you can see in the atomic model on the right, so that is conveniently 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 oz of francium is existing on earth at any given time.


Q:Francium decays too easily to formcompoundswith other elements. Which elements to friend think it would bond v if that could?

A:With one valence electron, francium would bond with a halogen element in team 17, which has actually seven valenceelectronsand requirements one more to fill its outer energy level. Aspects in team 17 incorporate fluorine and chlorine.

Summary

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

· because they have actually just one valence electron, team 1 elements are an extremely reactive. Together a result, they are uncovered in nature only in mix with other elements.

· Alkali metals are allsolidsat roomtemperature. Castle are relatively soft and low in density.

· from the top to the bottom of group 1, the elements have heavier, more reactiveatoms.

Explore More

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

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

From the height to the bottom of team 1, properties of the alkali metals adjust as follows:

1. Melting point __________.

2. Boiling point __________.

3. Thickness __________.

4. Atom radius __________.

5. Variety of electrons __________.

Review

1. What room alkali metals?

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

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

4. Compare and also contrast hydrogen and francium.

Alkaline earth Metals

Characteristics of group 2 the the regular table.

· recognize alkaline Earthmetals.

· list properties the alkaline Earthmetals.

· explain why alkaline Earthmetalsare really reactive.

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Sparklers choose the one this girl is holding do festive additions to countless celebrations. You might use lock yourself. But watch out if you do since their flames room really hot! The shining white flames are created when magnesium burns. Magnesium is a light- weight metal that burns in ~ a an extremely hightemperature. Other supplies of magnesium include flash photography, flares, and also fireworks. Magnesium is a steel in team 2 the the routine table, i m sorry you will certainly read around in this concept.  

The second Group

Barium (Ba) is one of sixelementsin group 2 that the routine table, i m sorry is presented below. Aspects in this group are calledalkaline earth metals. These steels are silver- or gray incolor. Lock are reasonably soft and also low in density, although no as soft and also lightweight as alkali metals. You have the right to watch a brief video clip introduction to the alkaline planet metals in ~ this URL:http://www.youtube.com/watch?v=DFQPnHkQlZM.

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Reactivity that Alkaline planet Metals

All alkaline earth metals have comparable properties due to the fact that they all have actually two valenceelectrons. Lock readily provide up their 2 valence electrons to achieve a complete outerenergy level, i beg your pardon is the many stable setup of electrons. As a result, castle are really reactive, although not fairly as reactive as the alkali metals in group 1. For example, alkaline planet metals will certainly react through coldwater, yet not explosively together alkali metals do. Since of your reactivity, alkaline planet metals never exist together puresubstancesin nature. Instead, they are constantly found linked with otherelements.

The reactivity of alkaline planet metals boosts from the height to the bottom of the group. That’s because theatomsget bigger native the peak to the bottom, therefore the valenceelectronsare farther indigenous the nucleus. As soon as valence electrons space farther from the nucleus, they space attracted less strongly by the cell nucleus and much more easily removed from the atom. This provides the atom much more reactive.

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

A:It takes much more energy to eliminate two valenceelectronsfrom an atom 보다 one valence electron. This provides alkaline earth metals through their two valence electrons much less reactive than alkali metals with your one valence electron.

Examples that Alkaline planet Metals

For a much better understanding of alkaline earth metals, let’s take a closer look at two of them: calcium (Ca) and also strontium (Sr). Calcium is a soft, gray, nontoxic alkaline planet metal. Back pure calcium doesn’t exist in nature, calciumcompoundsare an extremely common in Earth’s crust and also in seawater. Calcium is likewise the many abundant metal in the human body, emerging as calcium compound such as calcium phosphate and also calcium carbonate. These calcium compounds are discovered in bones and make castle hard and strong. The skeleton the the typical adult contains around a kilogram that calcium. Since calcium—like barium—absorbs x-rays, bones display up white in x-ray images. Calcium is crucial component that a healthy human diet. Great food resources of calcium are pictured inFigurebelow.

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Q:What health difficulties might result from a diet short in calcium?

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

Strontium is a silver-colored alkaline earth metal that is also softer 보다 calcium. Strontiumcompoundsare rather common and also have a range of uses—from fireworks come cement come toothpaste. In fireworks, strontium compounds produce deep red explosions. In toothpaste, favor the one pictured in theFigurebelow, the compound strontium chloride reduces tooth sensitivity.

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Summary

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

· Alkaline earth metals are an extremely reactive since they readily offer up their 2 valence electrons to accomplish a complete outerenergy level, which is the many stable setup of electrons. Reactivity boosts from the height to the bottom of the group.

· instances of alkaline earth metals include calcium, i beg your pardon is required for solid bones, and also strontium, which is used for making cement and other products.

Explore More

At the complying with URL, observe exactly how four different alkaline earth metals reaction withwater. After you watch the video, answer the inquiries below.

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

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

2. What describes the differences in reactivity?

3. Predict the reactivity that beryllium through water. Where would the fit in her ranking?

4. Whatsubstancesare created in each reaction the you observed in the video?

Review

1. What are alkaline planet metals? What space their physics properties?

2. Why space alkaline earth metals very reactive?

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

Noble Gases

Characteristics of team 18 the the periodic table.

· determine the noblegases.

· perform properties that noblegases.

· describe the nonreactivity the noblegasesand how it is concerned theoctet rule.

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Okay, helium balloons room light, but they’re not that light! This fanciful photo serves to make the suggest that helium is one of the lightestelements. Helium belongs come a team of facets called the noble gases.

What are Noble Gases?

Noble gasesare nonreactive, nonmetallicelementsin group 18 that the regular table. As you have the right to see in the routine table inFigurebelow, noble gases incorporate helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Every noble gases space colorless and odorless. They likewise have lowboilingpoints, explaining why they room gases at roomtemperature. Radon, in ~ the bottom that the group, is radioactive, so it constantly decays come otherelements. For great overview that the noble gases, clock the video clip at this URL:

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

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

· come explore specific noble gases, click on their signs in the periodic table at this URL:http://www.ptable.com/.

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Q:Based top top their place in the routine table (Figureabove), how numerous valenceelectronsdo you think noble gases have?

A:The variety of valenceelectronsstarts at one for aspects in team 1. That then boosts by one from left to right across each duration (row) the the routine table for groups 1–2 and 13–18. Therefore, noble gases have actually eight valence electrons.

Chemical properties of Noble Gases

Noble gases space the the very least reactive that all known elements. That’s since with eight valenceelectrons, your outer power levels room full. The only exemption is helium, which has just 2 electrons. Yet helium also has a full outerenergy level, because its only energy level (energy level 1) can hold a preferably of two electrons. A full outer power level is the many stable plan of electrons. Together a result, noble gases cannot become much more stable by reaction with other elements and also gaining or shedding valence electrons. Therefore, noble gases space rarely involved inchemical reactionsand practically never formcompoundswith various other elements.

Noble Gases and also theOctet Rule

Because the noble gases room the least reactive of all elements, your eight valence electrons are provided as the typical for nonreactivity and also to describe how other facets interact. This is proclaimed as the octet (“group of eight”) rule. Follow to this rule,atomsreact to formcompoundsthat permit them to have actually a team of eight valence electrons prefer the noble gases. For example, salt (with one valence electron) reacts v chlorine (with 7 valence electrons) to type the stable compound salt chloride (table salt). In this reaction, sodium donates an electron and also chlorine accepts it, offering each aspect an octet the valence electrons.

Some offers of Noble Gases

Did you ever get helium balloons choose those in the opened picture? uneven a balloon filled with air, a balloon filled with helium requirements to it is in weighted under so the won’t float away — although girlfriend don’t have to use one elephant!.

Q:Why walk a helium balloon float away if it’s no weighted down?

A:Heliumatomshave just twoprotons, twoneutrons, and also two electrons, for this reason they have less fixed than any other atoms except 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, prefer the one pictured in theFigurebelow, didn’t last an extremely long. The filaments quickly burned out. Back air to be pumped out of the bulb, the wasn’t a finish vacuum. Oxygen in the tiny amount the air continuing to be inside the light pear reacted v the metal filament. This corroded the filament and caused dark store on the glass. Pour it until it is full a light bulb through argon gas stays clear of these problems. That’s why modern light bulbs room filled v argon.

Q:How walk argon stop the troubles of at an early stage light bulbs?

A:As a noble gas through eight electrons, argon doesn’t react through the metal in the filament. This protects the filament and also keeps the glass blub complimentary of deposits.

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Noble gases are additionally used to fill the glass tubes of lighted signs like the one in theFigurebelow. Although noble gases room chemically nonreactive, your electrons can be energized by sending out anelectric currentthrough them. When this happens, the electrons jump to a higherenergy level. When the electrons go back to their original power level, they offer off energy as light. Different noble gases provide off irradiate of different colors. Neon provides off reddish-orange light, choose the native “Open” in the sign below. Krypton offers off violet light and also xenon provides off blue light.

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Summary

· Noble gases space nonreactive, nonmetallic aspects in team 18 the the regular table.

· Noble gases are the the very least reactive of every elements. That’s since they have eight valence electrons, which to fill their outerenergy level. This is the many stable arrangement of electrons, so noble gases rarely react with various other elements and formcompounds.

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

· Noble gases are used for balloons, light bulbs, and lighted signs.

Explore More

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

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

1. Compare and also contrast the reactivity that the aspects helium, neon, argon, krypton, and xenon.

2. To compare the density of these noble gases to the thickness of air.

3. Describe how the mass of noble gases changes from the height to the bottom of team 18.

Review

1. What are noble gases?

2. Define why noble gases space almost fully nonreactive.

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

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