assignments unit 3 component 3

Hydrogen and also alkali metals

Alkali earth metals

Nobel gases

Hydrogen and Alkali Metals

Characteristics of team 1 that the periodic table.

You are watching: What are the least reactive elements

· recognize theelementsin team 1 the the routine table.

· explain why team 1elementsare very reactive.

· List various other properties the alkalimetals.


You more than likely think ofwateras a substance that deserve to 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 continue in the photo above. About 3 pounds of salt were included to water, and the an outcome was this explosive reaction. Why is sodium such a reactive element? In this lesson friend will uncover out.

The an initial Group

Sodium (Na) is an element in group 1 that the regular table that the elements. This team (column) the the table is displayed below. It has the nonmetal hydrogen (H) and also sixmetalsthat are calledalkali metals. Facets in the same team of the periodic table have the same variety of valenceelectrons. These are the electrons in their outerenergy levelthat deserve to be affiliated in chemistry reactions. Valence electron determine plenty of of the properties of one element, so facets in the same group have similar properties. All the aspects in group 1 have just one valence electron. This renders them an extremely reactive.

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

A:With simply one valence electron, team 1 facets are “eager” to lose that electron. Law so allows them to attain a full outerenergy leveland maximum stability.


Reactivity of team 1 Elements

Hydrogen is a really reactive gas, and also the alkalimetalsare even an ext reactive. In fact, they are the many reactive steels and, in addition to the elements in group 17, room the most reactive of all elements. The reactivity that alkali metals boosts from the height to the bottom of the group, therefore lithium (Li) is the least reactive alkali metal and also francium (Fr) is the many reactive. Since alkali metals are for this reason reactive, they are discovered in nature just in combination with various other elements. Lock often incorporate with group 17 elements, which are an extremely “eager” to acquire an electron. At the URL below, you have the right to watch a video that mirrors just exactly how reactive the alkali steels are.


Other nature of Alkali Metals

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

· Alkali metals are allsolidsat roomtemperature.

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

· Alkali metals are reasonably soft. Some are even soft sufficient to reduced with a knife, choose the salt pictured in theFigurebelow.


A Closer Look

Although all team 1 facets share certain properties, such as being really reactive, they are not alike in every way. Three various group 1 elements are explained in an ext detail listed below (Figuresbelow,below, andbelow). An alert the means in which they different from one another.


Hydrogen has the smallest, lightest atom of every elements. Pure hydrogen is a colorless, odorless, tasteless gas that is nontoxic however highly flammable. Hydrogen gas exists largely as diatomic (“two-atom”) molecules (H2), as displayed in the chart on the right. Hydrogen is the most abundant facet in the universe and the 3rd most abundant element on Earth, emerging mainly in compound such together water.

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

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


Potassium is a soft, silvery metal that ignites explosively in water. It easily loses that is one valence electron to type positive potassium ion (K+), i beg your pardon are needed by every living cells. Potassium is so essential for plants the it is discovered in nearly all fertilizers, prefer the one shown here. Potassium is abundant in Earth’s late in minerals such together feldspar.


Francium has actually one that the largest, heaviest atom of every elements. That is one valence electron is far removed from the nucleus, together you can see in the atomic version on the right, so that is quickly removed native the atom. Francium is radioactive and quickly decays to form other elements such together radium. This is why francium is incredibly rare in nature. Much less than an oz of francium is current on planet at any given time.

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

A:With one valence electron, francium would bond with a halogen facet in group 17, which has seven valenceelectronsand demands one more to fill its outer energy level. Aspects in group 17 include fluorine and also chlorine.


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

· since they have just one valence electron, group 1 aspects are really reactive. Together a result, castle are discovered in nature only in combination with other elements.

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

· native the top to the bottom of group 1, the facets have heavier, an ext reactiveatoms.

Explore More

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


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

1. Melting point __________.

2. Boiling suggest __________.

3. Density __________.

4. Atom radius __________.

5. Number of electrons __________.


1. What are alkali metals?

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

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

4. Compare and also contrast hydrogen and francium.

Alkaline planet Metals

Characteristics of team 2 that the periodic table.

· recognize alkaline Earthmetals.

· perform properties of alkaline Earthmetals.

· define why alkaline Earthmetalsare an extremely reactive.


Sparklers prefer the one this girl is holding make festive enhancements to many celebrations. You may use lock yourself. But watch out if friend do due to the fact that their flames are really hot! The shining white flames are created when magnesium burns. Magnesium is a light- weight steel that burns at a very hightemperature. Other supplies 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 read around in this concept.  

The 2nd Group

Barium (Ba) is one of sixelementsin team 2 that the regular table, which is presented below. Facets in this group are calledalkaline earth metals. These steels are silver- or gray incolor. Lock are fairly 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 in ~ this URL:http://www.youtube.com/watch?v=DFQPnHkQlZM.


Reactivity of Alkaline planet Metals

All alkaline earth metals have similar properties due to the fact that they all have two valenceelectrons. Lock readily give up their 2 valence electrons to achieve a complete outerenergy level, which is the most stable plan of electrons. As a result, they are very reactive, return not fairly as reactive as the alkali metals in group 1. Because that example, alkaline planet metals will react through coldwater, but not explosively as alkali metals do. Since of your reactivity, alkaline earth metals never ever exist together puresubstancesin nature. Instead, they are always found an unified with otherelements.

The reactivity of alkaline earth metals boosts from the peak to the bottom the the group. That’s since theatomsget bigger indigenous the height to the bottom, therefore the valenceelectronsare farther from the nucleus. When valence electrons are farther from the nucleus, they room attracted much less strongly by the cell nucleus and more easily gotten rid of from the atom. This makes the atom an ext reactive.

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

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

Examples the Alkaline earth Metals

For a far better understanding the alkaline earth metals, let’s take it a closer look at 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 additionally the many abundant steel in the human being body, arising as calcium link such together calcium phosphate and calcium carbonate. This calcium compounds are discovered in bones and also make lock hard and also strong. The skeleton the the average adult contains around a kilogram the calcium. Because calcium—like barium—absorbs x-rays, bones present up white in x-ray images. Calcium is vital component that a healthy and balanced human diet. An excellent food resources of calcium space pictured inFigurebelow.


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

A:Children that don’t get enough calcium while their bones are developing may construct a deficiency disease called rickets, in which their bones room softer than normal and become bent and stunted. Adults who don’t get sufficient calcium may construct a problem called osteoporosis, in which the bones shed calcium and become weak and brittle. Human being with osteoporosis room at high risk of bone fractures.

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



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

· Alkaline planet metals are very reactive due to the fact that they readily give up their 2 valence electrons to achieve a full outerenergy level, i m sorry is the many stable arrangement of electrons. Reactivity boosts from the optimal to the bottom of the group.

· examples of alkaline planet metals encompass calcium, i beg your pardon is essential for strong bones, and also strontium, i m sorry is supplied for make cement and other products.

Explore More

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


1. Observe the reaction in the video, and also then rank the alkaline planet metals from most to least reactive through water.

2. What defines the distinctions in reactivity?

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

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


1. What are alkaline earth metals? What room their physics properties?

2. Why space alkaline planet metals very reactive?

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

Noble Gases

Characteristics of team 18 that the routine table.

· identify the noblegases.

· perform properties that noblegases.

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


Okay, helium balloons room light, but they’re not that light! This fanciful picture serves to do the suggest that helium is just one of the lightestelements. Helium belongs come a group of elements called the noble gases.

What space Noble Gases?

Noble gasesare nonreactive, nonmetallicelementsin team 18 the the periodic table. Together you have the right to see in the periodic table inFigurebelow, noble gases incorporate helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Every noble gases room colorless and odorless. They also have lowboilingpoints, explaining why they space gases in ~ roomtemperature. Radon, in ~ the bottom of the group, is radioactive, so the constantly decays come otherelements. For terrific overview the the noble gases, watch the video at this URL:


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

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


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

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

Chemical properties of Noble Gases

Noble gases are the least reactive of all well-known elements. That’s because with eight valenceelectrons, your outer energy levels room full. The only exception is helium, which has just two electrons. But helium also has a complete outerenergy level, due to the fact that its only energy level (energy level 1) deserve to hold a preferably of 2 electrons. A complete outer power level is the many stable arrangement of electrons. As a result, noble gases cannot become much more stable by reaction with other elements and gaining or losing valence electrons. Therefore, noble gases are rarely affiliated inchemical reactionsand almost never formcompoundswith other elements.

Noble Gases and theOctet Rule

Because the noble gases are the least reactive of every elements, their eight valence electrons are used as the traditional for nonreactivity and also to explain how other aspects interact. This is stated as the octet (“group of eight”) rule. Follow to this rule,atomsreact to formcompoundsthat enable them to have a team of eight valence electrons choose the noble gases. For example, salt (with one valence electron) reacts with chlorine (with 7 valence electrons) to form the secure compound salt chloride (table salt). In this reaction, sodium donates one electron and also chlorine accepts it, providing each aspect an octet that valence electrons.

Some supplies of Noble Gases

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

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

A:Heliumatomshave just twoprotons, twoneutrons, and also two electrons, so they have less fixed than any kind of other atoms except hydrogen. Together a result, helium is lighter 보다 air, explaining why a helium balloon floats up into the air uneven weighted down.

Early incandescent irradiate bulbs, choose the one pictured in theFigurebelow, didn’t last an extremely long. The filaments quickly burned out. Although air was pumped the end of the bulb, the wasn’t a finish vacuum. Oxygen in the little amount that air staying inside the light bulb reacted with the metal filament. This corroded the filament and caused dark deposits on the glass. Pour it until it is full a irradiate bulb with argon gas prevents these problems. That’s why modern-day light bulbs are filled with argon.

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

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


Noble gases are likewise used to fill the glass pipe of lighted signs like the one in theFigurebelow. Return noble gases space chemically nonreactive, your electrons have the right to be energized by sending out anelectric currentthrough them. When this happens, the electrons run to a higherenergy level. As soon as the electrons return to their original power level, they give off energy as light. Various noble gases provide off light of different colors. Neon offers off reddish-orange light, choose the indigenous “Open” in the sign below. Krypton gives off violet light and also xenon gives off blue light.



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

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

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

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

Explore More

Watch the video clip about noble gases at the following URL, and also then answer the concerns below.


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

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

3. Describe how the massive of noble gases changes from the peak to the bottom of group 18.


1. What are noble gases?

2. Describe why noble gases space almost totally nonreactive.

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

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