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assignments unit 3 part 3

Hydrogen and alkali metals

Alkali planet metals

Nobel gases

Hydrogen and Alkali Metals

Characteristics of group 1 the the routine table.

You are watching: Two highly reactive elements in period 2 are the metal lithium and the

· recognize theelementsin group 1 that the routine table.

· define why team 1elementsare really reactive.

· List other properties of alkalimetals.

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You probably think ofwateras a substance that have the right to put the end fires. But someelementsare therefore reactive that they burn in water. In fact, they basically explode in water. That’s what is keep going in the photo above. Around 3 pounds of sodium were included to water, and the result was this explosive reaction. Why is salt such a reactive element? In this lesson friend will find out.

The very first Group

Sodium (Na) is an aspect in team 1 the the regular table that the elements. This group (column) that the table is shown below. It has the nonmetal hydrogen (H) and sixmetalsthat are calledalkali metals. Aspects in the same team of the regular table have actually the same number of valenceelectrons. These room the electrons in their outerenergy levelthat deserve to be associated in chemistry reactions. Valence electrons determine plenty of of the properties of an element, so aspects in the same group have comparable properties. Every the elements in team 1 have actually just one valence electron. This renders them very reactive.

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

A:With simply one valence electron, group 1 facets are “eager” to shed that electron. Law so permits them to attain a complete outerenergy leveland maximum stability.

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Reactivity of group 1 Elements

Hydrogen is a very reactive gas, and also the alkalimetalsare even much more reactive. In fact, they are the many reactive metals and, together with the elements in team 17, space the many reactive of every elements. The reactivity the alkali metals increases from the optimal 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. Due to the fact that alkali metals are for this reason reactive, they are discovered in nature just in combination with other elements. They often incorporate with team 17 elements, which are very “eager” to gain an electron. At the URL below, you have the right to watch a video clip that reflects just just how reactive the alkali metals are.

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

Other properties of Alkali Metals

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

· Alkali steels are allsolidsat roomtemperature.

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

· Alkali steels are relatively soft. Some are even soft sufficient to reduced with a knife, favor the salt pictured in theFigurebelow.

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A Closer Look

Although all team 1 facets share details properties, such together being very reactive, they are not alike in every way. Three various group 1 facets are defined in an ext detail listed below (Figuresbelow,below, andbelow). Notification the means in which they differ from one another.

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Hydrogen has actually the smallest, lightest atoms of all elements. Pure hydrogen is a colorless, odorless, tasteless gas that is nontoxic but highly flammable. Hydrogen gas exists largely as diatomic (“two-atom”) molecules (H2), as shown in the diagram on the right. Hydrogen is the most abundant element in the universe and also the 3rd most abundant element on Earth, occurring mainly in compound such as water.


Q:Why do you think hydrogen gas normally exists together diatomic molecules?

A:Each hydrogen atom has just one electron. Once two hydrogenatomsbond together, they share a pair ofelectrons. The shared electrons fill their onlyenergy level, providing them the most stable arrangement of electrons.

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Potassium is a soft, silvery steel that ignites explosively in water. It easily loses that is one valence electron to kind positive potassium ion (K+), i beg your pardon are needed by every living cells. Potassium is so essential for plants the it is found in nearly all fertilizers, choose the one displayed here. Potassium is plentiful in Earth’s late in mineral such together feldspar.


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Francium has one of the largest, heaviest atom of all elements. That one valence electron is much removed native the nucleus, as you can see in the atomic model on the right, so the is conveniently removed indigenous the atom. Francium is radioactive and quickly decays to kind other aspects such as radium. This is why francium is incredibly rare in nature. Less than an ounce of francium is current on planet at any type of given time.


Q:Francium decays too quickly to formcompoundswith other elements. Which facets to you think it would certainly bond through if that could?

A:With one valence electron, francium would bond through a halogen element in team 17, which has actually seven valenceelectronsand requirements one an ext to fill its outer power level. Elements in team 17 incorporate fluorine and also chlorine.

Summary

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

· due to the fact that they have just one valence electron, group 1 aspects are an extremely reactive. Together a result, castle are uncovered in nature just in combination with other elements.

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

· native the peak to the bottom of team 1, the facets have heavier, more reactiveatoms.

Explore More

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

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

From the height to the bottom of group 1, properties of the alkali metals change as follows:

1. Melting allude __________.

2. Boiling suggest __________.

3. Thickness __________.

4. Atom radius __________.

5. Variety 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 aspects in team 17.

4. Compare and also contrast hydrogen and francium.

Alkaline planet Metals

Characteristics of group 2 the the regular table.

· identify alkaline Earthmetals.

· list properties of alkaline Earthmetals.

· describe why alkaline Earthmetalsare very reactive.

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Sparklers like the one this girl is holding make festive enhancements to plenty of celebrations. You may use lock yourself. But watch the end if girlfriend do since their flames are really hot! The shining white flames are created when magnesium burns. Magnesium is a light- weight metal that burns at a really hightemperature. Other uses of magnesium incorporate flash photography, flares, and also fireworks. Magnesium is a steel in team 2 that the regular table, i m sorry you will certainly read around in this concept.  

The 2nd Group

Barium (Ba) is just one of sixelementsin team 2 of the regular table, i m sorry is presented below. Facets in this team are calledalkaline earth metals. These metals are silver or gray incolor. Castle are relatively soft and low in density, although not as soft and lightweight together alkali metals. You can watch a brief video introduction come the alkaline planet metals in ~ this URL:http://www.youtube.com/watch?v=DFQPnHkQlZM.

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Reactivity of Alkaline earth Metals

All alkaline earth metals have comparable properties due to the fact that they all have two valenceelectrons. Castle readily offer up their 2 valence electron to achieve a full outerenergy level, i beg your pardon is the many stable plan of electrons. Together a result, they are an extremely reactive, back not rather as reactive as the alkali metals in group 1. Because that example, alkaline planet metals will react through coldwater, yet not explosively as alkali steels do. Since of your reactivity, alkaline earth metals never ever exist as puresubstancesin nature. Instead, lock are constantly found an unified with otherelements.

The reactivity of alkaline earth metals rises from the height to the bottom the the group. That’s because theatomsget bigger indigenous the peak to the bottom, so the valenceelectronsare farther indigenous the nucleus. As soon as valence electrons are farther indigenous the nucleus, they room attracted less strongly through the cell nucleus and more easily removed from the atom. This renders the atom more reactive.

Q:Alkali metals have just one valence electron. Why are alkaline planet metals much less reactive than alkali metals?

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

Examples of Alkaline earth Metals

For a much better understanding of alkaline planet metals, let’s take it a closer watch at two of them: calcium (Ca) and strontium (Sr). Calcium is a soft, gray, nontoxic alkaline planet metal. Return pure calcium doesn’t exist in nature, calciumcompoundsare really common in Earth’s crust and in seawater. Calcium is likewise the many abundant steel in the human being body, emerging as calcium compound such as calcium phosphate and calcium carbonate. These calcium compounds are found in bones and make them hard and strong. The skeleton the the median adult contains about a kilogram the calcium. Since calcium—like barium—absorbs x-rays, bones present up white in x-ray images. Calcium is vital component the a healthy and balanced human diet. Good food resources of calcium are pictured inFigurebelow.

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

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

Strontium is a silver-colored alkaline earth metal the is also softer than calcium. Strontiumcompoundsare quite common and have a variety of uses—from fireworks come cement to toothpaste. In fireworks, strontium compounds develop deep red explosions. In toothpaste, like the one pictured in theFigurebelow, the link strontium chloride reduces this sensitivity.

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Summary

· aspects in team 2 the the periodic table are called alkaline planet metals. They are silvery or gray incolor. They room also relatively soft and low in density.

· Alkaline earth metals are an extremely reactive since they readily provide up their 2 valence electron to attain a full outerenergy level, which is the most stable plan of electrons. Reactivity increases from the optimal to the bottom that the group.

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

Explore More

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

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

1. Watch the reactions in the video, and then location the alkaline planet metals from many to least reactive with water.

2. What explains the differences in reactivity?

3. Suspect the reactivity that beryllium through water. Where would it fit in your ranking?

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

Review

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

2. Why space alkaline earth metals really reactive?

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

Noble Gases

Characteristics of group 18 of the routine table.

· determine the noblegases.

· perform properties of noblegases.

· define the nonreactivity of noblegasesand how it is concerned theoctet rule.

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Okay, helium balloons space light, however they’re no that light! This fanciful photo serves to do the point that helium is among the lightestelements. Helium belongs to a group of facets called the noble gases.

What space 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 include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and also radon (Rn). Every noble gases room colorless and also odorless. They also have lowboilingpoints, explaining why they are gases at roomtemperature. Radon, in ~ the bottom the the group, is radioactive, so that constantly decays come otherelements. For an excellent overview of the noble gases, clock the video clip at this URL:

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

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

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

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

A:The number of valenceelectronsstarts in ~ one for aspects in group 1. It then boosts by one from left come right across each period (row) that the regular table for groups 1–2 and 13–18. Therefore, noble gases have actually eight valence electrons.

Chemical nature of Noble Gases

Noble gases space the the very least reactive that all recognized elements. That’s since with eight valenceelectrons, your outer power levels space full. The only exception is helium, which has just 2 electrons. But helium additionally has a complete outerenergy level, because its only energy level (energy level 1) have the right to hold a preferably of 2 electrons. A complete outer power level is the many stable setup of electrons. As a result, noble gases cannot become much more stable by reacting with other elements and gaining or shedding valence electrons. Therefore, noble gases are rarely connected inchemical reactionsand nearly never formcompoundswith other elements.

Noble Gases and theOctet Rule

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

Some uses of Noble Gases

Did you ever before get helium balloons like those in the opening picture? unequal a balloon filled through air, a balloon filled v helium requirements to it is in weighted under so it won’t float far — although you don’t need to use one elephant!.

Q:Why does a helium balloon float far if it’s no weighted down?

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

Early incandescent light bulbs, choose the one pictured in theFigurebelow, didn’t last an extremely long. The filaments quickly melted out. Return air to be pumped out of the bulb, it wasn’t a finish vacuum. Oxygen in the small amount of air remaining inside the light bulb reacted with the metal filament. This corroded the filament and also caused dark shop on the glass. Pour it until it is full a irradiate bulb with argon gas prevents these problems. That’s why modern light bulbs space filled through argon.

Q:How go argon stop the problems of early light bulbs?

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

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Noble gases are likewise used to to fill the glass tubes of lighted signs like the one in theFigurebelow. Back noble gases room chemically nonreactive, their electrons have the right to be energized by sending out anelectric currentthrough them. When this happens, the electrons jump to a higherenergy level. As soon as the electrons return to their original energy level, they give off energy as light. Various noble gases give off light of various colors. Neon gives off reddish-orange light, like the word “Open” in the authorize below. Krypton offers off violet light and also xenon gives off blue light.

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Summary

· Noble gases room nonreactive, nonmetallic facets in group 18 the the routine table.

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

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

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

Explore More

Watch the video clip about noble gases at the adhering to URL, and 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 facets helium, neon, argon, krypton, and 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 height to the bottom of team 18.

Review

1. What space noble gases?

2. Describe why noble gases are almost fully nonreactive.

See more: The Spinal Tract That Relays Information Concerning Pain And Temperature To The Cns Is The

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

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