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assignments unit 3 component 3

Hydrogen and alkali metals

Alkali earth metals

Nobel gases

Hydrogen and Alkali Metals

Characteristics of team 1 that the regular table.

You are watching: What are the two most reactive groups in the periodic table

· recognize theelementsin team 1 the the periodic table.

· define why team 1elementsare really reactive.

· List other properties of alkalimetals.

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

The an initial Group

Sodium (Na) is an element in team 1 the the periodic table of the elements. This group (column) the the table is presented below. It has the nonmetal hydrogen (H) and also sixmetalsthat room calledalkali metals. Facets in the same team of the regular table have actually the same variety of valenceelectrons. These space the electrons in your outerenergy levelthat have the right to be associated in chemical reactions. Valence electrons determine plenty of of the nature of an element, so elements in the same group have similar properties. Every the facets in team 1 have just one valence electron. This makes them an extremely reactive.

Q:Why does having actually just one valence electron make group 1 elements very reactive?

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

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Reactivity of group 1 Elements

Hydrogen is a really reactive gas, and also the alkalimetalsare even much more reactive. In fact, they room the most reactive metals and, together with the facets in group 17, are the many reactive of all elements. The reactivity the alkali metals rises from the optimal to the bottom of the group, therefore lithium (Li) is the the very least reactive alkali metal and also francium (Fr) is the many reactive. Due to the fact that alkali metals are therefore reactive, they are discovered in nature only in combination with various other elements. They often integrate with group 17 elements, i beg your pardon are really “eager” to obtain an electron. At the URL below, you have the right to watch a video that shows just exactly how reactive the alkali metals are.

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

Other properties of Alkali Metals

Besides being an extremely reactive, alkali steels share a variety of other properties.

· Alkali metals are allsolidsat roomtemperature.

· Alkali steels are low in density, and some of them float onwater.

· Alkali steels are fairly soft. Part are also soft enough to reduced with a knife, favor the salt pictured in theFigurebelow.

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A Closer Look

Although all group 1 aspects share specific properties, such together being really reactive, they space not alike in every way. Three different group 1 facets are described in more detail listed below (Figuresbelow,below, andbelow). An alert the means in i m sorry they different from one another.

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Hydrogen has actually the smallest, lightest atom of all elements. Pure hydrogen is a colorless, odorless, tasteless gas the is nontoxic however highly flammable. Hydrogen gas exists mostly as diatomic (“two-atom”) molecule (H2), as displayed in the chart on the right. Hydrogen is the many abundant aspect in the universe and the third most abundant element on Earth, developing mainly in compound such together water.


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

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

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Potassium is a soft, silvery metal that ignites explosively in water. It conveniently loses that one valence electron to type positive potassium ions (K+), i m sorry are required by all living cells. Potassium is so essential for plants that it is found in nearly all fertilizers, prefer the one displayed here. Potassium is numerous in Earth’s crust in mineral such as feldspar.


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Francium has one that the largest, heaviest atoms of every elements. Its one valence electron is far removed from the nucleus, as you have the right to see in the atomic version on the right, so the is quickly removed native the atom. Francium is radioactive and quickly decays to kind other aspects such together radium. This is why francium is very rare in nature. Less than an ounce of francium is present on planet at any kind of given time.


Q:Francium decays too conveniently to formcompoundswith various other elements. Which aspects to girlfriend think it would bond through if the could?

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

Summary

· group 1 of the periodic table consists of hydrogen and also the alkali metals.

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

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

· from the optimal to the bottom of team 1, the aspects have heavier, more reactiveatoms.

Explore More

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

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

From the top to the bottom of team 1, properties of the alkali metals change as follows:

1. Melting suggest __________.

2. Boiling point __________.

3. Thickness __________.

4. Atom radius __________.

5. Number of electrons __________.

Review

1. What are alkali metals?

2. Why is hydrogen, a nonmetal, put in the same team as the alkali metals?

3. Define why team 1 elements often formcompoundswith aspects in team 17.

4. Compare and contrast hydrogen and francium.

Alkaline planet Metals

Characteristics of group 2 the the routine table.

· identify alkaline Earthmetals.

· list properties that alkaline Earthmetals.

· describe why alkaline Earthmetalsare really reactive.

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Sparklers favor the one this girl is holding do festive enhancements to countless celebrations. You might use lock yourself. Yet watch out if girlfriend do because their flames space really hot! The glowing white flames are created when magnesium burns. Magnesium is a light- weight metal that burns at a very hightemperature. Other offers of magnesium incorporate flash photography, flares, and also fireworks. Magnesium is a metal in group 2 of the routine table, i m sorry you will certainly read about in this concept.  

The 2nd Group

Barium (Ba) is among sixelementsin team 2 that the routine table, i beg your pardon is presented below. Elements in this group are calledalkaline earth metals. These steels are silver- or gray incolor. Lock are reasonably soft and also low in density, although not as soft and also lightweight together alkali metals. You have the right to watch a brief video clip introduction come the alkaline planet metals at 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 since they all have two valenceelectrons. Castle readily offer up their 2 valence electron to achieve a complete outerenergy level, i beg your pardon is the most stable arrangement of electrons. Together a result, castle are an extremely reactive, back not rather as reactive as the alkali metals in team 1. Because that example, alkaline planet metals will react v coldwater, however not explosively as alkali steels do. Because of your reactivity, alkaline planet metals never exist together puresubstancesin nature. Instead, castle are always found merged with otherelements.

The reactivity the alkaline planet metals boosts from the height to the bottom of the group. That’s since theatomsget bigger from the top to the bottom, so the valenceelectronsare farther indigenous the nucleus. As soon as valence electrons room farther native the nucleus, they space attracted less strongly through the cell nucleus and an ext easily gotten rid of from the atom. This renders the atom an ext reactive.

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

A:It takes more energy to eliminate two valenceelectronsfrom one atom than one valence electron. This makes alkaline planet metals through their two valence electrons less reactive than alkali metals with their one valence electron.

Examples of Alkaline earth Metals

For a much better understanding of alkaline earth metals, let’s take it a closer look at at 2 of them: calcium (Ca) and strontium (Sr). Calcium is a soft, gray, nontoxic alkaline earth metal. Although pure calcium doesn’t exist in nature, calciumcompoundsare really common in Earth’s crust and also in seawater. Calcium is additionally the most abundant metal in the person body, arising as calcium compounds such as calcium phosphate and also calcium carbonate. This calcium compound are discovered in bones and also make lock hard and also strong. The skeleton of the typical adult contains around a kilogram that calcium. Due to the fact that calcium—like barium—absorbs x-rays, bones present up white in x-ray images. Calcium is critical component of a healthy human diet. Great food sources of calcium room pictured inFigurebelow.

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Q:What health troubles might an outcome from a diet short in calcium?

A:Children that don’t get sufficient calcium while your bones are developing may build a deficiency disease called rickets, in which your bones space softer than normal and become bent and stunted. Adults that don’t get enough calcium may build a condition called osteoporosis, in which the bones shed calcium and become weak and also brittle. People 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 variety of uses—from fireworks come cement to 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

· aspects in group 2 the the routine table are dubbed alkaline earth metals. They room silvery or gray incolor. They are also fairly soft and also low in density.

· Alkaline planet metals are really reactive because they readily give up their two valence electron to accomplish a complete outerenergy level, i m sorry is the many stable plan of electrons. Reactivity boosts from the peak to the bottom the the group.

· examples of alkaline planet metals include calcium, which is required for solid bones, and strontium, i m sorry is provided for make cement and also other products.

Explore More

At the adhering to URL, observe how four different alkaline earth metals react withwater. After ~ you watch the video, answer the inquiries below.

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

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

2. What explains the distinctions in reactivity?

3. Guess the reactivity of beryllium v water. Where would it fit in her ranking?

4. Whatsubstancesare developed in each reaction that you observed in the video?

Review

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

2. Why room alkaline planet metals very reactive?

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

Noble Gases

Characteristics of team 18 of the regular table.

· identify the noblegases.

· list properties the noblegases.

· explain the nonreactivity that noblegasesand just how it is related to theoctet rule.

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Okay, helium balloons are light, however they’re not that light! This fanciful snapshot serves to make the suggest that helium is among the lightestelements. Helium belongs come a group of facets called the noble gases.

What room Noble Gases?

Noble gasesare nonreactive, nonmetallicelementsin group 18 that the routine table. As you have the right to see in the regular table inFigurebelow, noble gases encompass helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and also radon (Rn). All noble gases are colorless and also odorless. They also have lowboilingpoints, explaining why they room gases in ~ roomtemperature. Radon, at the bottom that the group, is radioactive, so the constantly decays come otherelements. For an excellent overview the the noble gases, clock the video 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.

· to explore details noble gases, click their signs in the regular table in ~ this URL:http://www.ptable.com/.

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

A:The number of valenceelectronsstarts at one for elements in group 1. That then rises by one native left come right across each period (row) the the periodic table for groups 1–2 and 13–18. Therefore, noble gases have actually eight valence electrons.

Chemical nature of Noble Gases

Noble gases are the the very least reactive the all well-known elements. That’s because with eight valenceelectrons, your outer power levels are full. The only exemption is helium, which has actually just two electrons. Yet helium additionally has a complete outerenergy level, due to the fact that its only power level (energy level 1) can hold a preferably of two electrons. A complete outer power level is the many stable setup of electrons. As a result, noble gases cannot become an ext stable by reacting with other elements and also gaining or shedding valence electrons. Therefore, noble gases space rarely affiliated inchemical reactionsand practically never formcompoundswith other elements.

Noble Gases and also theOctet Rule

Because the noble gases room the least reactive of every elements, your eight valence electron are offered as the conventional for nonreactivity and to describe how other elements interact. This is proclaimed as the octet (“group that eight”) rule. Follow to this rule,atomsreact come formcompoundsthat enable them to have actually a team of eight valence electrons choose the noble gases. For example, sodium (with one valence electron) reacts through chlorine (with 7 valence electrons) to form the stable compound sodium chloride (table salt). In this reaction, sodium donates an electron and also chlorine accepts it, providing each element an octet that valence electrons.

Some uses of Noble Gases

Did you ever get helium balloons favor those in the opening picture? unequal a balloon filled v air, a balloon filled with helium demands to it is in weighted down so the won’t float far — although friend don’t need to use an elephant!.

Q:Why does a helium balloon float far if it’s not weighted down?

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

Early incandescent light bulbs, choose the one pictured in theFigurebelow, didn’t last really long. The filaments quickly shed out. Although air was pumped the end of the bulb, the wasn’t a complete vacuum. Oxygen in the small amount that air staying inside the light pear reacted with the metal filament. This corroded the filament and caused dark shop on the glass. Pour it until it is full a light bulb v argon gas avoids these problems. That’s why modern light bulbs room filled with argon.

Q:How does argon protect against the problems of beforehand 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 additionally used to to fill the glass pipe of lighted signs like the one in theFigurebelow. Back noble gases space chemically nonreactive, their electrons deserve to be energized by sending anelectric currentthrough them. When this happens, the electrons run to a higherenergy level. When the electrons return to their original energy level, they give off energy as light. Different noble gases give off irradiate of different colors. Neon gives off reddish-orange light, like the indigenous “Open” in the sign below. Krypton offers off violet light and also xenon offers off blue light.

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Summary

· Noble gases room nonreactive, nonmetallic aspects in group 18 the the regular table.

· Noble gases space the least reactive of all elements. That’s because they have actually eight valence electrons, which to fill their outerenergy level. This is the many stable setup of electrons, for this reason noble gases rarely react with various other elements and also formcompounds.

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

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

Explore More

Watch the video clip about noble gases in ~ the complying with URL, and then answer the questions below.

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

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

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

3. Define how the massive of noble gases transforms from the optimal to the bottom of group 18.

Review

1. What are noble gases?

2. Define why noble gases are almost fully nonreactive.

See more: A Stitch In Time Saves Nine Meaning, Why Do People Say “A Stitch In Time Saves Nine”

3. What is the octet rule? just how is it concerned noble gases?

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