assignments unit 3 part 3

Hydrogen and alkali metals

Alkali planet metals

Nobel gases

Hydrogen and also Alkali Metals

Characteristics of group 1 the the regular table.

You are watching: Which of the following elements is the most reactive?

· recognize theelementsin group 1 the the regular table.

· describe why group 1elementsare an extremely reactive.

· List various other properties the alkalimetals.


You probably think ofwateras a substance that can put out fires. However someelementsare therefore reactive the they burn in water. In fact, they practically explode in water. That’s what is keep going in the photo above. About 3 pounds of salt 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 uncover out.

The first Group

Sodium (Na) is an facet in team 1 of the periodic table of the elements. This team (column) the the table is presented below. It contains the nonmetal hydrogen (H) and also sixmetalsthat room calledalkali metals. Elements in the same team of the periodic table have the same variety of valenceelectrons. These room the electrons in their outerenergy levelthat have the right to be involved in chemistry reactions. Valence electrons determine plenty of of the properties of one element, so facets in the same group have comparable properties. All the facets in group 1 have just one valence electron. This provides them an extremely reactive.

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

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


Reactivity of team 1 Elements

Hydrogen is a an extremely reactive gas, and the alkalimetalsare even an ext reactive. In fact, they are the most reactive metals and, in addition to the facets in team 17, are the many reactive of all elements. The reactivity that alkali metals rises from the peak to the bottom of the group, so lithium (Li) is the the very least reactive alkali metal and also francium (Fr) is the many reactive. Because alkali metals are for this reason reactive, lock are found in nature only in combination with other elements. Lock often integrate with team 17 elements, i m sorry are an extremely “eager” to get an electron. In ~ the URL below, you can watch a video clip that shows just exactly how reactive the alkali metals are.


Other properties of Alkali Metals

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

· Alkali metals are allsolidsat roomtemperature.

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

· Alkali metals are reasonably soft. Some are also soft enough to cut with a knife, choose the salt pictured in theFigurebelow.


A Closer Look

Although all group 1 aspects share certain properties, such together being an extremely reactive, they space not alike in every way. Three various group 1 elements are explained in much more detail listed below (Figuresbelow,below, andbelow). An alert the methods in which they differ from one another.


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

Q:Why carry out you think hydrogen gas generally exists together diatomic molecules?

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


Potassium is a soft, silvery steel that ignites explosively in water. It quickly loses that one valence electron to type positive potassium ion (K+), which are needed by all living cells. Potassium is so important for plants that it is discovered in virtually all fertilizers, like the one presented here. Potassium is numerous in Earth’s late in mineral such together feldspar.


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

Q:Francium decays too easily 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 bond through a halogen aspect in group 17, which has seven valenceelectronsand demands one an ext to fill its outer power level. Facets in group 17 include fluorine and also chlorine.


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

· due to the fact that they have just one valence electron, group 1 facets are really reactive. As a result, they are discovered in nature only in mix with other elements.

· Alkali metals are allsolidsat roomtemperature. They are reasonably soft and also low in density.

· indigenous 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.” usage the data in the team 1 table to to fill in the blanks listed below with eitherincreasesordecreases.


From the optimal to the bottom of group 1, nature of the alkali metals adjust as follows:

1. Melting suggest __________.

2. Boiling point __________.

3. Density __________.

4. Atomic radius __________.

5. Variety of electrons __________.


1. What space alkali metals?

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

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

4. Compare and also contrast hydrogen and francium.

Alkaline earth Metals

Characteristics of team 2 the the routine table.

· determine alkaline Earthmetals.

· list properties of alkaline Earthmetals.

· explain why alkaline Earthmetalsare very reactive.


Sparklers favor the one this girl is holding make festive enhancements to numerous celebrations. You might use them yourself. Yet watch the end if girlfriend do since their flames are really hot! The bright white flames are created when magnesium burns. Magnesium is a light- weight steel that burns at a really hightemperature. Other uses of magnesium include flash photography, flares, and also fireworks. Magnesium is a metal in team 2 the the periodic table, i m sorry you will read about in this concept.  

The second Group

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


Reactivity the Alkaline planet Metals

All alkaline planet metals have similar properties since they all have actually two valenceelectrons. They readily give up their 2 valence electrons to attain a full outerenergy level, i m sorry is the most stable plan of electrons. Together a result, they are an extremely reactive, return not rather as reactive as the alkali steels in group 1. For example, alkaline planet metals will certainly react through coldwater, yet not explosively as alkali steels do. Due to the fact that of their reactivity, alkaline earth metals never exist as puresubstancesin nature. Instead, castle are always found merged with otherelements.

The reactivity the alkaline planet metals rises from the optimal to the bottom that the group. That’s because theatomsget bigger native the top to the bottom, therefore the valenceelectronsare farther indigenous the nucleus. As soon as valence electrons space farther indigenous the nucleus, they space attracted less strongly by the cell core and much more easily eliminated from the atom. This renders the atom more reactive.

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

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

Examples that Alkaline earth Metals

For a better understanding of alkaline earth metals, let’s take it a closer look at at 2 of them: calcium (Ca) and also strontium (Sr). Calcium is a soft, gray, nontoxic alkaline planet 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 steel in the human being body, developing as calcium link such together calcium phosphate and also calcium carbonate. These calcium link are found in bones and also make lock hard and also strong. The skeleton the the typical adult contains around a kilogram the calcium. Because calcium—like barium—absorbs x-rays, bones show up white in x-ray images. Calcium is vital component the a healthy human diet. Good food sources of calcium are pictured inFigurebelow.


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

A:Children that don’t get sufficient calcium while their bones are forming may build a deficiency disease called rickets, in which your bones are softer than normal and also become bent and also stunted. Adults that don’t get enough calcium may build a problem called osteoporosis, in i beg your pardon the bones lose calcium and become weak and brittle. Civilization with osteoporosis space at high danger of bone fractures.

Strontium is a silver-colored alkaline planet metal the is also softer than calcium. Strontiumcompoundsare fairly common and have a selection of uses—from fireworks to cement come toothpaste. In fireworks, strontium compounds produce deep red explosions. In toothpaste, choose the one pictured in theFigurebelow, the compound strontium chloride reduces this sensitivity.



· facets in group 2 that the regular table are referred to as alkaline planet metals. They are silvery or gray incolor. They are also relatively soft and also low in density.

· Alkaline earth metals are an extremely reactive since they readily provide up their two valence electrons to accomplish a complete outerenergy level, i m sorry is the most stable setup of electrons. Reactivity boosts from the peak to the bottom of the group.

· instances of alkaline earth metals encompass calcium, i beg your pardon is needed for strong bones, and also strontium, which is offered for do cement and other products.

Explore More

At the following URL, observe how four various alkaline planet metals reaction withwater. ~ you clock the video, price the questions below.


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

2. What defines the differences in reactivity?

3. Predict the reactivity that beryllium v water. Wherein would the fit in her ranking?

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


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

2. Why space alkaline earth metals an extremely reactive?

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

Noble Gases

Characteristics of team 18 that the routine table.

· recognize the noblegases.

· list properties of noblegases.

· describe the nonreactivity that noblegasesand exactly how it is pertained to theoctet rule.


Okay, helium balloons space light, but they’re no that light! This fanciful snapshot serves to make the allude that helium is one of the lightestelements. Helium belongs to a team of elements called the noble gases.

What room Noble Gases?

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


· come learn 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 icons in the periodic table at this URL:http://www.ptable.com/.


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

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

Chemical properties of Noble Gases

Noble gases space the least reactive of all recognized elements. That’s since with eight valenceelectrons, your outer energy levels space full. The only exemption is helium, which has actually just two electrons. Yet helium additionally has a complete outerenergy level, because its only power level (energy level 1) deserve to hold a preferably of two electrons. A complete outer power level is the many stable arrangement of electrons. As a result, noble gases cannot become more stable by reacting with other elements and gaining or losing valence electrons. Therefore, noble gases room rarely affiliated inchemical reactionsand virtually never formcompoundswith other elements.

Noble Gases and theOctet Rule

Because the noble gases are the the very least reactive of all elements, their eight valence electron are used as the conventional for nonreactivity and also to define how other facets interact. This is stated as the octet (“group that eight”) rule. Follow to this rule,atomsreact to formcompoundsthat allow them to have a team of eight valence electrons like the noble gases. Because that example, salt (with one valence electron) reacts v chlorine (with seven valence electrons) to type the steady compound salt chloride (table salt). In this reaction, sodium donates an electron and chlorine accepts it, giving each facet an octet the valence electrons.

Some uses of Noble Gases

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

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

A:Heliumatomshave just twoprotons, twoneutrons, and two electrons, therefore they have less fixed than any other atoms other than hydrogen. As a result, helium is lighter 보다 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 really long. The filaments quickly burned out. Back air was pumped out of the bulb, it wasn’t a complete vacuum. Oxygen in the tiny amount the air staying 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 v argon gas prevents these problems. That’s why modern-day light bulbs space filled v argon.

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

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


Noble gases are additionally used to to fill the glass tube of lighted signs like the one in theFigurebelow. Back noble gases are chemically nonreactive, their electrons have the right to be energized by sending anelectric currentthrough them. As soon as this happens, the electrons run to a higherenergy level. Once the electrons go back to their original power level, they provide off energy as light. Different noble gases give off irradiate of various colors. Neon provides off reddish-orange light, prefer the indigenous “Open” in the authorize below. Krypton offers off violet light and xenon offers off blue light.



· Noble gases room nonreactive, nonmetallic elements in team 18 of the regular table.

· Noble gases space the least reactive of every elements. That’s since they have actually eight valence electrons, which to fill their outerenergy level. This is the most stable setup of electrons, for this reason noble gases hardly ever react with other elements and formcompounds.

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

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

Explore More

Watch the video about noble gases at the complying with URL, and also then prize the questions below.


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

2. Compare the thickness of this noble gases come the density of air.

3. Explain how the massive of noble gases changes from the peak to the bottom of team 18.


1. What room noble gases?

2. Explain why noble gases are almost totally nonreactive.

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

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