assignments unit 3 part 3

Hydrogen and also alkali metals

Alkali earth metals

Nobel gases

Hydrogen and Alkali Metals

Characteristics of group 1 of the routine table.

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

· determine theelementsin group 1 that the regular table.

· describe why group 1elementsare an extremely reactive.

· List various other properties that alkalimetals.


You probably think ofwateras a problem that deserve to put out fires. But someelementsare therefore reactive the they burn in water. In fact, they virtually explode in water. That’s what is happening in the picture above. About 3 pounds of sodium were added to water, and the result 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 element in group 1 that the routine table the the elements. This group (column) the the table is displayed below. It contains the nonmetal hydrogen (H) and sixmetalsthat space calledalkali metals. Elements in the same team of the routine table have the same number of valenceelectrons. These are the electron in your outerenergy levelthat can be affiliated in chemical reactions. Valence electron determine many of the nature of an element, so facets in the same group have comparable properties. All the elements in team 1 have actually just one valence electron. This renders them really reactive.

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

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


Reactivity of team 1 Elements

Hydrogen is a an extremely reactive gas, and also the alkalimetalsare even much more reactive. In fact, they room the most reactive metals and, together with the facets in team 17, are the many reactive of every elements. The reactivity that alkali metals boosts from the top to the bottom of the group, for this reason lithium (Li) is the the very least reactive alkali metal and francium (Fr) is the many reactive. Because alkali metals are so reactive, castle are uncovered in nature only in combination with other elements. Castle often incorporate with team 17 elements, which are an extremely “eager” to obtain an electron. In ~ the URL below, you can watch a video clip that shows just how reactive the alkali steels are.


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 metals are relatively soft. Part are even soft sufficient to reduced with a knife, choose the salt pictured in theFigurebelow.


A Closer Look

Although all team 1 aspects share particular properties, such as being very reactive, they room not alike in every way. Three various group 1 elements are described in an ext detail below (Figuresbelow,below, andbelow). An alert the means in which they differ from one another.


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 presented in the diagram on the right. Hydrogen is the many abundant facet in the universe and also the 3rd most abundant element on Earth, developing mainly in link such together water.

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

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


Potassium is a soft, silvery steel that ignites explosively in water. It quickly loses that one valence electron to form positive potassium ion (K+), which are necessary by all living cells. Potassium is so necessary for plants that it is found in virtually all fertilizers, like the one shown here. Potassium is numerous in Earth’s tardy in minerals such as feldspar.


Francium has actually one the the largest, heaviest atom of all elements. Its one valence electron is much removed from the nucleus, as you have the right to see in the atomic version on the right, so that is easily removed from the atom. Francium is radioactive and quickly decays to kind other aspects such together radium. This is why francium is extremely rare in nature. Much less than an oz of francium is current on planet at any kind of given time.

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

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


· team 1 the the regular table consists of hydrogen and the alkali metals.

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

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

· native the height to the bottom of team 1, the elements have heavier, an ext reactiveatoms.

Explore More

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


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

1. Melting suggest __________.

2. Boiling point __________.

3. Density __________.

4. Atom radius __________.

5. Number of electrons __________.


1. What room alkali metals?

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

3. Define why group 1 aspects often formcompoundswith aspects in group 17.

4. Compare and also contrast hydrogen and francium.

Alkaline planet Metals

Characteristics of group 2 the the routine table.

· determine alkaline Earthmetals.

· perform properties the alkaline Earthmetals.

· define why alkaline Earthmetalsare very reactive.


Sparklers like the one this girl is holding do festive enhancements to countless celebrations. You might use them yourself. But watch out if you do because their flames room really hot! The bright white flames are produced when magnesium burns. Magnesium is a light- weight metal that burns at a very hightemperature. Other offers of magnesium incorporate flash photography, flares, and fireworks. Magnesium is a steel in group 2 of the periodic table, i beg your pardon you will certainly read about in this concept.  

The second Group

Barium (Ba) is among sixelementsin group 2 of the periodic table, i m sorry is shown below. Facets in this team are calledalkaline planet metals. These steels are silver- or gray incolor. Castle 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 come the alkaline earth metals in ~ this URL:http://www.youtube.com/watch?v=DFQPnHkQlZM.


Reactivity that Alkaline earth Metals

All alkaline earth metals have comparable properties since they all have actually two valenceelectrons. They readily provide up their 2 valence electron to achieve a complete outerenergy level, i m sorry is the many stable arrangement of electrons. Together a result, castle are an extremely reactive, back not quite as reactive together the alkali steels in team 1. Because that example, alkaline planet metals will react with coldwater, yet not explosively together alkali steels do. Since of your reactivity, alkaline planet metals never exist together puresubstancesin nature. Instead, lock are always found merged with otherelements.

The reactivity that alkaline earth metals rises from the height to the bottom that the group. That’s due to the fact that theatomsget bigger from the top to the bottom, for this reason the valenceelectronsare farther from the nucleus. As soon as valence electrons are farther from the nucleus, they space attracted much less strongly through the nucleus and more easily gotten rid of from the atom. This provides the atom an ext reactive.

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

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

Examples of Alkaline earth Metals

For a far better understanding the alkaline planet metals, let’s take it a closer watch at 2 of them: calcium (Ca) and also 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 additionally the many abundant metal in the person body, developing as calcium compound such together calcium phosphate and also calcium carbonate. These calcium compounds are discovered in bones and make lock hard and also strong. The skeleton the the mean adult contains about a kilogram that calcium. Since calcium—like barium—absorbs x-rays, bones show up white in x-ray images. Calcium is an essential component that a healthy human diet. An excellent food resources of calcium space pictured inFigurebelow.


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

A:Children that don’t get enough calcium while their bones are creating may develop a deficiency disease called rickets, in which their bones room softer 보다 normal and become bent and also stunted. Adults who don’t get enough calcium may build a condition called osteoporosis, in i beg your pardon the bones shed calcium and become weak and also brittle. People with osteoporosis room at high hazard of bone fractures.

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



· facets in team 2 of the routine table are called alkaline planet metals. They are silvery or gray incolor. They are also relatively soft and low in density.

· Alkaline earth metals are really reactive due to the fact that they readily provide up their two valence electrons to attain a complete outerenergy level, i m sorry is the many stable plan of electrons. Reactivity increases from the peak to the bottom the the group.

· examples of alkaline earth metals encompass calcium, which is needed for strong bones, and strontium, i m sorry is supplied for make cement and other products.

Explore More

At the following URL, observe how four different alkaline earth metals reaction withwater. ~ you clock the video, answer the inquiries below.


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

2. What explains the distinctions in reactivity?

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

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


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

2. Why room 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 routine table.

· identify the noblegases.

· perform properties of noblegases.

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


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

What are Noble Gases?

Noble gasesare nonreactive, nonmetallicelementsin group 18 that the periodic 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 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 the the group, is radioactive, so it constantly decays to otherelements. For great overview that the noble gases, watch the video at this URL:


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

· to explore particular noble gases, click on their symbols in the periodic table at this URL:http://www.ptable.com/.


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

A:The variety of valenceelectronsstarts at one for elements in group 1. The then increases by one indigenous left come right throughout each duration (row) the the regular table for teams 1–2 and 13–18. Therefore, noble gases have actually eight valence electrons.

Chemical properties of Noble Gases

Noble gases are the the very least reactive of all recognized elements. That’s since with eight valenceelectrons, your outer energy levels room full. The only exception is helium, which has just two electrons. Yet helium also has a complete outerenergy level, due to the fact that its only power level (energy level 1) can hold a best of two electrons. A full outer energy level is the many stable setup of electrons. Together a result, noble gases cannot become more stable by reacting with other elements and also gaining or losing valence electrons. Therefore, noble gases are rarely affiliated inchemical reactionsand almost never formcompoundswith other elements.

Noble Gases and also theOctet Rule

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

Some offers of Noble Gases

Did you ever before get helium balloons prefer those in the opened picture? uneven a balloon filled v air, a balloon filled with helium needs to be weighted under so it won’t float far — although friend don’t need to use one elephant!.

Q:Why does 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 less massive than any type of other atoms other than hydrogen. Together a result, helium is lighter 보다 air, explaining why a helium balloon floats up into the air uneven weighted down.

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

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

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


Noble gases are also used to to fill the glass tube of lighted signs like the one in theFigurebelow. Return noble gases are chemically nonreactive, your electrons have the right to be energized by sending out anelectric currentthrough them. As soon as this happens, the electrons run to a higherenergy level. As soon as the electrons return to their original energy level, they offer off energy as light. Different noble gases provide off light of various colors. Neon provides off reddish-orange light, like the word “Open” in the authorize below. Krypton provides off violet light and xenon provides off blue light.



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

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

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

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

Explore More

Watch the video about noble gases at the following URL, and then price the concerns below.


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

2. Compare the density of these noble gases come the density of air.

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


1. What are noble gases?

2. Explain why noble gases room almost completely nonreactive.

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

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