Science Chemistry Question!?!?
1. Why are ALKALI metals so reactive?
2. Why are NOBLE GASES so unreactive?
3. Explain and give an example of: qualitative properties, quantitative properties.
4. calculate the density of a material of mass 15.8g and volume 9.2cm^3.
5. Define alloy and give an example. What are the benefits of alloys?
Answer:
hey,
U wont find any of these answers on net that easily...
following are the solutions to the above problems...
ANSWERS
Ans-1)
Alkali metals are very reactive because they have very less ionization energy.Ioniztion energy is the amount of anergy required to remove an electron from an gaeous atom.So, the valence electron can be removed very easily( with less energy)...So thats y they are reactive....
for example...Elements like potassium and Sodium are so reactive that they catch fire when exposed in air....
Ans-2)
Nobel gases are very unreactive becuse they have fully filled electronic configuration..no more electron can be added and very high energy is required to remove the valence shell electron..It has Zero electron affinity.
Ans-3)
basically.Qualitative properties are properties that are observed and can generally not be measured. It should be mentioned that qualitative properties are most of the time at least as important as quantitative properties. Qualitative factors are also sometimes referred to as: 'untouchable' factors.
A quantitative property is one that exists in a range of magnitudes, and can therefore be measured. Measurements of any particular quantitative property are expressed as a specific quantity, referred to as a unit, multiplied by a number. Examples of physical quantities are distance, mass, and time.
Ans-4)
we know that density=mass/volume
so using the above formula...we can say that...
density = 15.8/9.2
density = 1.71 g/cm^3
Ans-5)
An alloy is a homogeneous mixture of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. The resulting metallic substance usually has different properties (sometimes significantly different) from those of its components.
for example
Steel is an alloy consisting mostly of iron, with a carbon content between 0.02% and 1.7 or 2.04% by weight (C:1000–10,8.67Fe), depending on grade
Alloys are usually prepared to improve on the properties of their components
The following are the properties and the advantage of useing the alloys.
density, reactivity and electrical and thermal conductivity are greatly improved...
Engineering properties, such as tensile strength, shear strength and Young's modulus are also improved
In simple laymans language..
an alloy is formed this way...
i a normal strucutre of a compunt ...there are some defects.so some other elemnts with same size as that of the earlire compound replaced the atoms .
ans this way we get an alloy.....
Hope this is the best answer...
all the best....
1. Why are ALKALI metals so reactive?
Alkali metals are the most reactive metals. They only have one valence electron, and thus want to get rid of that electron as much as possible in order to form a stable octet. This explains why it is extremely reactive. Alkali metals form ionic compounds with non-metals (such as halogens)
2. Why are NOBLE GASES so unreactive?
Noble gases have eight valence electrons (stable octet). They do not need to gain or lose any electrons (0 combining capacity), so they will are completely unreactive.
3. Explain and give an example of: qualitative properties, quantitative properties.
Qualitative properties include viscosity, clarity, malleability, ductility, brittleness, colour, etc.
Quantitative properties can be measured and include boiling/melting point, density, mass.
4. calculate the density of a material of mass 15.8g and volume 9.2cm^3.
Density is mass/volume
1.7g/cm^3
5. Define alloy and give an example. What are the benefits of alloys?
An alloy is technically a solution of different metals that have been mixed in order to obtain the required properties. An example would be cupronickel. With alloys, we get to select desired properties of different metals (such as hardness, resistance to rust, etc.) and combine them.
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