Using English To Compare : The Elements

Compare the Element

 

    
 

Is a chemical element that can not be subdivided into smaller substance, or can not be converted into other chemical substances using ordinary chemical methods. The smallest particle of an element is an atom. An atom consists of a nucleus of an atom (nucleus) surrounded by electrons. Atom consists of a nucleus of protons and neutrons. Until now there are approximately 117 known elements in the world.

A.    Understanding the Elements

To understand the meaning of the elements, you try to pay attention to the things that are around. The objects that exist in this world either solid, liquid or gas is the material, because it has mass and occupies space. To be able to recognize the material around is not difficult, you can use the senses that you have, like using your hands to feel the shape of solid and liquid materials, and use the sense of smell to identify the material in the form of gas.

The material can also be said of substances, because they both have mass and occupy space. However, have you ever imagined what form the materials around you? because if you notice, the material seems composed of the same substance and uniform, it turns out there is also a material that is composed of a variety of substances that are not uniform. The material is composed of a variety of substances that are not uniform commonly referred to as a compound or mixture. While the material is composed of a single uniform substance, it was called by the elements. For example, water is a material in the form of compounds consisting of two hydrogen atoms and one oxygen, forming water chemical formula H2O. Since water is a compound that can still be parsed hydrogen and oxygen, the water is not an element. So, what exactly is that element?

To understand the elements, you try to watch back in the chemical formula of water is H2O, then if the water is decomposed through chemical reactions, then didapatlah hydrogen and oxygen, and it is called with the elements, the elements hydrogen, and the element oxygen, because between hydrogen and oxygen can not be further elaborated into other simple substance through simple chemical reactions. Thus, the element is a single substance that can not be broken down into other substances simple through simple chemical reactions.

In the open, just a few elements that stand alone as a single agent, the rest of these elements react with other elements to form a compound or mixture.

Here are some common elements identified:

 

No	Elements	No	Elements
1	Aluminum	23	Cobalt
2	Antimony	24	Chromium
3	Arsen	25	Lithium
4	Barium	26	Magnesium
5	Sulfur	27	Manganese
6	Beryllium	28	Mercury
7	Iron	29	Sodium
8	Bismuth	30	Nickel
9	Boron	31	Nitrogen
10	Brom	32	Oxygen
11	Gold	33	Silver
12	Fluor	34	Platina
13	Phosphorus	35	Radium
14	Helium	36	Seng
15	Hydrogen	37	Cerium
16	Iodine	38	Cesium
17	Iridium	39	Silicon
18	Cadmium	40	Copper
19	Potassium	41	Lead
20	Calcium	42	Lead
21	Carbon	43	Tungsten
22	Chlorine	44	Uranium

In normal conditions, many of these elements in the form of solids, such as copper, gold, iron, and lead. Mercury or better known as mercury and bromine are examples of elements that are liquid. Oxygen and nitrogen are examples of gaseous elements.

Here are eight kinds of elements that make up almost 99% of the earth's crust.

Elements	Percentage (%)
Aluminum	8,1
Iron	5
Potassium	2,6
Calcium	3,6
Magnesium	2,1
Sodium	2,9
Oxygen	46,6
Silicon	27,7
Othere Elements	1,4

Grouping and Attributes Element

A.Grouping Elements of Chemistry

Following the development of the periodic table grouping from time to time.

1.           Grouping element based on the nature of the metal and nonmetal

This grouping is still common for most of the elements that have been Found at that time include metal (± 70%). The following properties are used as a reference in the grouping:

• metal properties include:

- Can be thermally and electrically

- Easily molded (forged and moved like a wire)

- Shiny, especially if rubbed

- generally solid at room temperature

- Characteristically reductant

• The non-metallic properties include:

- Can not thermally and electrically

- It is hard to be formed

- Not shiny (opaque)

- Some are solid, liquid, and gas at room temperature

- Characteristically oxidizer

2.           The grouping of the elements by Triad Dobreiner

In 1817, John Wolfgang Dobreiner arrange the elements into three groups based on the increase of atomic mass (mass number), in which the atomic mass of the middle element is the average of the atomic masses first and third elements. Dobreiner invention which explains the similarity of these three properties of each element group.

example:

Li Na K

3.           grouping element based on the Law of Octaves Newlands

1864 Newlands groups elements by relative atomic mass ascension.

Examples of the periodic table:

1H 2Li 3BE 4B 5C 6N 7O

8F 9NA 10mg 11Al 12Si 14S 13P

In Newlands table there are the noble gases because at that time the noble gas has not been found. Noble gas was first discovered by Rayleig and Ramsay in 1894, the Argon gas.

 Newlands weakness octave grouping elements such as suitable only for elements with atomic mass is small and there are some elements coincident, ie in one place there are two elements.

4.           The modern periodic table

Before you found this periodic table, in 1871, Dmitri Ivanovich Mendeleev had already made the table the elements are arranged regularly (periodically) so-called elements of the periodic table called the periodic table of the elements. Then in 1915 Henry Moseley has successfully completed the periodic table Mendeleev and is now called the modern periodic table of the results of research (1887-1915).

The modern periodic table is also called the length of the periodic table, is a refinement of the Mendeleev periodic table. The difference, Mendeleev periodic table is based on the increase in mass numbers, while the modern periodic table is based on the increase in number of atoms. Grouping of elements based on equal nature. There are some things that underlie grouping of chemical elements, namely the nature of the metal, valence electron, and the number of electron shells.

Based on the nature of the metal, chemical elements are grouped into metal, semilogam, and non-metallic.

Based on the valence electrons, the chemical elements are grouped into main groups and transition. The main group consists of 8 groups, namely IA, IIA, IIIA, IVA, VA, VIA, VIIA, and VIIIA. The transition classes can be subdivided into groups in the transition, lanthanide and actinide.

Based on the number of its electron shell, chemical elements can be grouped into seven periods, ie the period 1-7. Metal properties during the same elements from left to right are increasingly to be non-metallic.

B.    Nature Chemical Elements

The properties of the chemical elements are divided into physical properties and chemical properties. Physical properties include shape, color, hardness, solubility ,, electrical conductivity and heat, the density, magnetic properties, atomic radius, heat of vaporization, boiling and melting points. While the chemical properties include reactivity of the elements.

1.      Elements of Alkali and Alkali Metals Group Land

The elements in the class of alkali and alkaline earth metals include elements golonggan IA (3Li 11Na 37Rb 19K 55Cs 87Fr) and IIA (12mg 4BE 20Ca 38Sr 56Ba 88Ra). The following about the properties of metal elements:

Physical properties of Alkali Metal Elements of Soil

The nature of Li Na K Rb Cs

atomic number 3 11 19 37 55

Atomic radius (pm) 155 190 235 248 267

The radius of the ion M + (pm) 60 95,133,148,169

The melting point (0C) 181 97.8 63.6 38.9 28.4

Boiling point (0C) 1,347 883 774 688 678

The density (g / cm3) 0.53 0.97 0.86 1.59 1.90

Hardness (Mohs scale) 0.6 0.4 0.5 0.3 0.3

Flash Color Purple Red Red Yellow Blue

Chemical Properties of the Elements Alkali

The nature of Li Na K Rb Cs

atomic number 4 12 20 38 56

Atomic radius (pm) 90 130 174 192 198

The radius of the ion M + (pm) 3 65 99,113,135

The melting point (0C) 1,278 649 839 769 725

Boiling point (0C) 2,970 1,090 1,484 1,384 1,640

The density (g / cm3) 1.86 1.72 1.55 2.54 3.59

Hardness (Mohs scale) 5 2.0 1.5 1.8 2

Color Red Red White White flame green old

Chemical Properties of the Elements Alkali soil

The nature of Li Na K Rb Cs

The electron configuration [He] 2S1 [Ne] 3s1 [Ar] 4s1 [Kr] 5s2 [Xe] 6s1

First ionization energy (kJ / mole) 519 498 418 401 376

Electronegativities 1.0 0.9 0.8 0.8 0.7

Standard electrode potential (volt) -3.045 -2.714 -2.925 -2.925 -2.923

From the statement above we can conclude the following:

1)      Class alkali (IA)

a)      Having one of the outermost electron (ns1)

low ionization energy (easily release electrons).

strong reducing agent (susceptible to oxidation).

highly reactive (in nature there is no free element).

reaction with water quickly.

low melting point (soft), because the metal bond is weak.

b) Atomic radius greater the further down:

further down the reactivity increases.

further downward alkaline stronger.

further down the lower the melting point.

c) The metals obtained from electrolysis of fused alkali halide salt.

d) compounds bind alkali ions, are solid, and has a high melting point

e) Reaction flames: Na yellow K purple

f) All alkali-soluble compounds in the water.

2)      Class alkaline earth (IIA)

a)      Has two outer electrons (ns2):

ionization energy is low, but lower IA.

strong reducing agent, though not as strong as IA.

highly reactive, but more reactive IA.

reaction with water is slow.

sufficiently high melting point (hard), because the metal bond is stronger than IA.

b)      Atomic radius greater the further down: further down the reactivity increases.

further downward alkaline stronger.

further down the lower the melting point.

c)      The metals obtained from electrolysis of fused alkali halide salt.

d)     compounds bind alkali ions, are solid, and has a high melting point

e)      Reaction flame: red Sr

Ba green.

f)       C1- compound, 2-, and N03 of the IIA dissolve well in water.

C032- compound of IIA nothing is soluble. The solubility of compounds of the IIA 2- 504 further down the smaller (more soluble). Solubility base (OH-) of the IIA

greater the further down (more soluble).

2.      Elements Transition Metals Group

Transition elements can be defined as the elements which has sub-d or f subshell partially filled. Transition element consists of Sc (Scandium), Ti (Titanium), V (Vanadium), Cr (Chromium), Mn (Manganese), Fe (iron), Co (cobalt), Ni (nickel), Cu (copper) and Zn (Zinc). All the elements of the transition metals have the nature, this occurs because more transition elements have unpaired electrons.

The common trait:

The oxidation state positive definite,

In general, the price has an oxidation state of more than 1, except Sc (+3) and Zn (+2)

In general, the ion-colored, except SC2 +, Zn2 + and Ti4 +,

Can form a complex ion as central atom.

Has a very strong metallic bond

Are catalysts (accelerate the reaction).

Its boiling and melting points increase from 1.541oC transition elements (scandium) to 1890 ° C (Vanadium), then down to 1,083 ° C (Copper) and 420 ° C (Zinc).

The compounds of the transition elements having more than one oxidation number. The existence of more than one oxidation number is due simply to release valence electrons. Thus, the ionization energy of the first, second and so have a relatively smaller price than the main group elements.

Most of the elements and transition metal compounds are paramagnetic (attracted by the magnetic field) and instead is diamagnetic (not attracted by the magnetic field).

Most of transition metal ions in color.

3.      Elements of nonmetal

1)      Elements Group Halogen

Halogens are a group of chemical elements residing in group VIIa of the periodic table. This group of: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and elements ununseptium (Uus) undiscovered. Halogen denotes elements which produce salt by reaction with metals. The term is derived from the scientific term French from the 18th century which was adapted from the Greek.

The nature of the elements of this group are:

a.       Highly reactive (strong oxidant), toxic.

Oxidants: F2> Cl2> Br2> I2

Reducing agents: I-> Br-> Cl-> F-

b.      Pale yellow gas F2, Cl2 gas greenish brown liquid Br2, I2 easy menyublin purple-black solid.

c.       F2: reacts with water, remove the O2

d.      Cl 2: undergo disproportionation,

e.       Br 2: most soluble,

f.       I2: soluble, remain soluble both in alcohol (iodine tincture: antiseptic)

g.      Their atomic radius from the bottom up is getting smaller.

h.      Elektronegatifanya from left to right increases.

i.        Ionosasi energy dadari greater left to right.

j.        Electron affinity smaller from the bottom up.

2)      Elements Noble Gas Group

The noble gases are the VIIIA group elements (18) in the periodic table. So-called noble because these elements are very stable (very difficult to react). General nature of this group are:

Not colored, odorless, tasteless, slightly soluble in water.

Have 8 valence electrons and valence electrons on Helium 2, the noble gases are eternal and were given a zero valence.

Molecules consisting of a single atom (monoatom).

3)      The element carbon

Carbon is an element that lies in the period of 2 groups IVA in the periodic system.

Elemental carbon at room temperature (298? K, 1 atm) solid form in the form of crystals, consisting of many carbon atoms are covalently bound. Physical properties of the carbon can be observed in the following table:

nature Description

The melting point (° C) 3500

Boiling point (° C) 3930

Covalent radii of 0.77

Ionic radii of 0.15

Color (charcoal) Black

In general, the chemical nature of carbon are as follows. Very reactive, if it reacts, no inclination to lose carbon atoms outermost electrons to form C4 + ion. Some reactions including the following element carbon. Carbon there is forming organic compounds and there is also a form of inorganic compounds. Among the organic compounds in hydrocarbons, alcohols, aldehydes, ketones, esters and carboxylic acids, inorganic carbon compounds in anataranya oxides, carbides, carbonates, sulfides, and halides. Has several allotropes of carbon atoms, which form a structure different from the same atom, such as graphite, diamond, fuleren, bulkyball, and charcoal. Carbon in the form of H2CO3 can be ionized compounds (soluble) in water. Has the ionization energy of 11.3 kJ / mol. Keelektrponegatifan has a value of 2.5.

4)      Elements Nitrogen

Situated in the period of 3 groups VA, are gaseous at standard room temperature.

Physical properties of nitrogen:

nature Description

melting point (° C) -210

Boiling point (oC) -196

covalent radii (A) 0.75

ionic radii (N3 +) (A) 1.71

ionic radii (N5 +) (A) 0.11

color at room temperature colorless gas

Chemical properties of nitrogen:

Less reactive, seen from the many processes in nature that do not involve oxygen nitrogen but although the biggest composition of air is nitrogen (78%). Here are some reactions of nitrogen. Can act as an oxidizing agent (oxidizer) and a reducing agent (reductant). Nitrogen as an oxidizer has an oxidation state of -1, -2, and -3, while as a reducing agent has an oxidation state of +1, +2, +3, +4, and +5. The most common oxidation state of the nitrogen is -3, +3 and +5. Has the ionization energy of 14.5 kJ / mol. Has a value of electronegativity of 3.0.

5)      Oxygen Elements

Located in the 3 groups VIA period. Berwuju gas at room temperature: 298 K, 1 atm.

Physical properties of the element oxygen:

nature Description

melting point (° C) -218.8

Boiling point (oC) -183.0

covalent radii (A) 0.73

ionic radii (O2) (A) 1.4

color at room temperature colorless gas

Chemical properties of the element oxygen

The outermost electrons have as many as six electrons in an oxidation state of -2. Having 2 allotropes, namely oxygen gas (O2) and ozone (O3). Undergo oxidation reactions with most of the elements forming oxides (eg Na2O), peroxide (eg Na2O2), superoxide (example: NaO2), and carbon compounds. Has the ionization energy of 14.5 kJ / mol. Has a value of electronegativity of 3.0.

4.      Elements of the Third Period

The elements which occupy the third period, among others, Na, Mg, Al, Si, P, S, Cl, and Ar. General properties of the sequential elements from Na to Ar is as follows:

The fingers are getting smaller because of the number of valence e- more.

Metal properties on the wane

Reduced alkalinity, acidity increases

The nature of the reductant is reduced, increasing oxidizer

The ionization energy increases

Electronegativities increases

Kelogaman: Na, Mg, Al (metal), Si (semilogam), P, S, Cl, Ar (instead of metal)

The more oxidation

Conductor: Na, Mg, Al. Insulators are: Si, P, S, Cl, Ar

Strength bases: the more acidic