CONVERSATION BETWEEN TEACHERS AND STUDENTS ABOUT CHEMICAL LESSONS "HALOGEN"
Teacher : Good morning!
Students : morning sir
Teacher : Well, our children will start our learning process, our material today is the element of halogen.
Before that who can mention what elements of the element include halogens?
Before that who can mention what elements of the element include halogens?
Student 1 : me sir,will try to answer what are the halogen elements. The halogen elements include fe, cl, br, i, and at
Teacher : Is that right, do you know any more about halogens?
Student 2 : The halogen is a reactive element of the bush and is present in group 7a.
Teacher : That's right, so the halogens are a reactive element, and we can call them a 7 a and can be found in the form of anoragic salts
Student 3 : why is the halogen element said to be highly reactive sir?
Teacher : since the halogen element has an electron configuration ns2 np5, otherwise it has oxidation -1 except f which is always univalent. Has everything got it?
Students : already sir.
Teacher : well I am enough for today, we continue next week.
Does the halogen element form a compound? Give me an example ..
BalasHapusThe Halogen element is a highly reactive element so that halogens are found in nature in the form of their compounds, namely:
Hapus1. Salt Form
A.Halogen + element of salt metal Example:
Br2 + 2 Na (s) à 2 NaBr (s)
3 Cl2 + 2 Fe (s) à 2 FeCl3 (l)
B.Asam halide + base Salt Halide + air
Example:
HCl + NaOH à NaCl + H2O
HBr + NaOH à NaBr + H2O
2. Form of Acid
A.Asam Halide (HX)
Formed from halogen that is resistant to hydrogen to form hydrogen halide.
H2 + X2 à 2 HX
Example:
H2 + Cl2 à 2 HCl
H2 + I2 à 2 HI
Fluorine and chlorine are quickly accompanied by explosions, and bromine and iodine slowly.
B. Oksihalida acid (HXO)
Formed only on halogens that have positive oxidation numbers that are illuminated with air.
Example of oxide reaction with air:
Cl2O + H2O à2 HCl
Cl2O3 + H2O à 2 HClO2
Cl2O5 + H2O à 2 HClO3
Cl2O7 + H2O à 2 HClO4
3. Antarhalogenic compounds
X2 + nY2 2XYn
Halogen with large electronegativity + Halogen with small Keeloktronegatiafan
Between Halogens can undergo chemical reactions. Since the oxidizing force decreases from Fluorine to Iod, Halogen can oxidize the lower Halide Ion (displacement reaction). Thus, reactions occurring between halogens can be summarized in the following statements:
1. F2 can oxidize Cl- to Cl2, Br- to Br2, and I- to I2.
2. Cl2 can oxidize Br- to Br2, and I-be I2. Cl2 can not oxidize F- to F2.
3. Br2 can oxidize I-to I2. Br2 can not oxidize F- to F2 or Cl- into Cl2.
4. I2 can not mengokisdasi F- to F2, Cl- to Cl2, and Br-become Br2.
4. Halogen oxide
All halogens can form oxide compounds. Fluorine can form oxides OF2 and O2F2, known as fluoride oxygen. The O2F2 compound is prepared by rapidly passing F2 gas through a 2% NaOH solution. The O2F2 compound is an orange yellow solid used as a rocket fuel.
5. Halide Compounds
Halide compounds are halogen compounds with oxidation -1 numbers, and are the most numerous compounds among halogen compounds. Generally can be grouped into hydrogen halide compounds and halide salts.
How are chemical and physics properties of halogen class?
BalasHapusA). Physical Properties
Hapus1. The value of atomic radius increases from F to At
2. The value of ionisation energy decreases from F to At
3. The value of the electronegativity decreases from F to At
3. The electron's effectivity decreases from F to At, except for a slight fluctuation of adri F to Cl (a negative sign means energy is released). The decrease in electron affinity can be understood from the value of the radius of the atom which increases with the addition of the atomic shell, the exception to F. This is because the electrons are so close together that it generates a strong repulsive rejection with the electrons of other atoms when the other electrons are absorbed by the F atom. Thus, the tendency of F-ions is less than expected.
Halogen has an oxidation number, except F with 2 oxidation numbers.
B). Chemical Properties
Halogen Reactivity
F (g) + e F- (g) -> H = -328 kJ
Cl (g) + e Cl- (g) -> H = -349 kJ
In the above reaction we can see that the electron affinity of the halogen element is reduced from top to bottom, ie chlorine to iodine. This happens because the increase of atomic radius, but H (energy) fluorine is lower than chlorine, this deviation occurs because of the small fluorine atoms, which makes a repulsive force between electrons.
Reactions to Halogen
Halogen is a highly reactive element. Halogen elements can react with all elements, even muia gas. In fact, fire-retardant substances such as water and asbestos can burn in fluorine gas.
1. Reaction with metal
2. Reaction with Hydrogen
3. Reactions with non-metals
4. Reaction with hydrocarbons
5. Reaction with water
6. Reactions with bases
7. Reaction between halogen
why we have to study about electron configuration ?
BalasHapusWe study the electron configuration, so we know the number of electrons in each atomic shell. In addition, with the understanding of electron configurations we are able to understand atomic structures based on bohr atomic theory, elemental properties, relative atomic mass and periodic elemental properties in the periodic table.
BalasHapusWhy is the 7A or halogen group having the greatest electron affinity?
BalasHapusThe electron affinity is the amount of energy liberated by a neutral atom in the form of a gas. The value of electron affinity for some elements in one class and one irregular period. For example, elements in classes IIIA, IVA, and VA. Nevertheless, in general the periodicity of electron affinities can be concluded, ie in one period, from left to right, the electron affinity tends to increase. As in one class, from the bottom up, the affinity of electrons tends to increase.
BalasHapusAll major group elements have negative electron affinities. Except for alkaline earth elements (IIA) and noble gases (VIIIA). The greatest electron affinity belongs to the halogen (VIIA) element because it is the easiest element to capture electrons. Thus, the element with the greatest electron affinity is Fluorine with an affinity value of -328.0.
Of which elements,which one the most reactiv?
BalasHapusMention the use of halogen?
BalasHapusThe use of halogen in everyday life are:
Hapus1. Use of haolgen: Fluorine
-Polymer CF2CF2 is used as a nonstick coating on a teflon pan.
- Toothpaste contains fluoride compounds to prevent tooth decay.
-Fluorine is used as a coolant (refrigerant)
2. The use of hogen: chlorine
-Cl2 is a raw material for making PVC plastic (CH2CHCl).
-NaOCl is used as bleach clothing, antiseptics, and in low concentrations for sterilizing baby bottles.
-Clorine (Cl2) is added to drinking water and swimming pools form HCl and HOCl compounds. Both have high oxidation power and can kill bacteria. Cl2 (g) + H2O (l) -> HCl (aq) + HOCl (aq)
-NaClO3 is used to eradicate wild plants, chlorine for bleach paper, dry-cleaning agent and for bromine production
-KCl for mixture in pesticides
3. Use of halogen: bromine
-AgBr (and AgI) are light-sensitive and are used in photographic and X-ray films. In the process, the compound will be reduced to Ag and halogens where Ag will blacken the paper.
- Bromine compounds are used in pesticides, pharmaceuticals and in the manufacture of refractory plastic and textiles.
-Etylene bromide, C2H4Br2, mixed into leaded gasoline to bind lead (Pb) so as not to stick to the machine.
4. The use of haolgen: iodine
Iodine compounds (NaI, NaIO3, KI, and KIO3) are also added to the kitchen salt to prevent mumps and mental retardation.
-Iodin is used to create polarization filters on sunglasses, to reduce glare.
Iodine is an antiseptic dissolved into alcohol and applied to the wound