Chemistry

Compounds in Chemistry: Characteristics of Compounds

len Alfred Ajibola - Sat, 15th February, 2020 @ 19:27

Topics in Chemistry

Le Chatelier's Principle: Changes in concentration and pressure in dynamic equilibrium Chemical Equilibrium: Dynamic Equilibrium in Chemistry Static and Dynamic Equilibrium explained with their Differences Chemistry Scheme of Work, SS1, First Term Chemistry Scheme of Work, SS1, Second Term Chemistry Scheme of Work, SS1, Third Term Compounds in Chemistry: Characteristics of Compounds Types of Mixture: Homogenous and Heterogeneous Mixtures Mixtures: Characteristics of Mixtures Physical Properties of Matter explained with Examples Chemical Properties of Matter explained with Examples Differences between Physical and Chemical Change Ionic Theory and Electrolysis Physical and Chemical Properties of Acids States of Matter: Characteristics of Solids Liquid State of Matter: Characteristics of Liquids Gaseous State of Matter: Characteristics of Gases Molar Mass, Worked Examples and Differences with Molecular Mass Elements: Characteristics of Elements Salts and Types of Salt in Chemistry


Academic Questions in Chemistry

Please check out our Test Your Knowledge page to see all Questions and Answers

Which of the following isn't an element of the periodic table.

  • A. J

  • B. Y

  • C. W

  • D. B

  • E. U

  • F. K

According to the periodic table, elements in the same group have got the same number of shells.

  • A. True

  • B. False

The periodic table of elements is also called the Mendeleev's table.

  • A. True

  • B. False

The simplest formula of a compound is termed _____.

  • A. Emperical formula

  • B. Molecular formula

  • C. Avogadro's number

  • D. Mass formula

  • E. Molar mass formula

  • F. Mole ratio

A compound composed of iron (Fe) and oxygen (O) was analyzed and found to contain 69.94% iron and 30.06% oxygen. Find the empirical formula of the compound. (Molar mass of Fe=55.85, O=16)

  • A. FeO

  • B. Fe2O3

  • C. Fe3O4

  • D. FeO2

  • E. Fe3O6

  • F. Fe2O4

Which of the following statement is false concerning hydrocarbons?

  • A. Hydrocarbons can be aromatic

  • B. Hydrocarbons are made up of carbon and hydrogen only

  • C. Alkynes are aliphatic hydrocarbons

  • D. Alkenes have a carbon-carbon double bond in their structure

  • E. Benzene ring has a carbon-carbon triple bond in its structure

  • F. Hydrocarbons are the main constituents of petroleum and natural gas

The ability of carbon to form long chain of itself is called _____.

  • A. Carbon chain reaction

  • B. Catenation

  • C. Carbontion

  • D. Carbontion

  • E. Organic chemistry

  • F. Carbon moleculation

Calculate the relative molecular mass of methane. (Carbon = 12.001, H = 1.00794).

  • A. 13.00894 amu

  • B. 11.00206 amu

  • C. 12.00794 amu

  • D. 14.001 amu

  • E. 15.001 amu

  • F. 16.033 amu

LEN ACADEMY SMART SCHOOL SOFTWARE

Image

Read more on its smart academic features here

Please click here to kindly support education


What is a Compound?

Compounds are not elements, rather they are formed from elements. A compound is a substance formed from the chemical combination of two or more elements.

Please read on Elements and their Characteristics here.

As an instance, water (H2O) is a compound formed from the elements - hydrogen and oxygen. We can also correctly say that water is formed from hydrogen molecule and oxygen molecule respectively. This is true because both gases (hydrogen and oxygen) will always exist as molecules. To this end, reactive elements that exists as molecules at room temperature will also form compounds.

Note: Water is neither hydrogen nor oxygen, rather it is a compound formed from hydrogen and oxygen molecules in the ratio 2:1. This is shown in the equation below:


Once a compound is formed, it is very difficult to revert it to the constituent elements that formed it. As a result, the change that accompanies the formation of a compound is termed a chemical change.

Please read more on Physical and Chemical Changes here.

Below are some reactions that show the formation of compounds from elements:

Na(s) + Cl(g) -> NaCl(s) - Formation of Sodium Chloride from the reaction between Sodium and Chlorine.

2Fe(s) + 3O2 -> Fe2O3(s) - Formation of Iron(III)oxide from the reaction between Iron and Oxygen.

C(s) + O2 -> CO2(g) - Formation of Carbon(IV)oxide from the reaction between Carbon and Oxygen.

You can read on Dalton's Atomic Theory and it's Modifications here.


Characteristics of Compounds

An understanding on the characteristics of compounds will give you a clue towards comprehending what compounds really are.

Below are some Characteristics or Features of Compounds:


  1. Compounds will always have a constant composition in terms of atomic mass and elemental make-up. For instance, water (H2O) is a compound and will always have an atomic mass of 18.01528g/mol. In addition, it will always be composed of hydrogen and oxygen in the ratio 2:1.
    Please read on Molecular Mass and Solved Questions on Molecular Mass here.

  2. Compounds always have a different chemical property from its constituent elements. For instance, H2O is different from Hydrogen (H) and Oxygen (O) respectively. As a result, it has a different chemical property from both constituent elements.
    Please read more on the Chemical Properties of Matter here.

  3. The elements that make up a compound cannot be separated by ordinary physical process. As an instance, common salt (NaCl) cannot be separated into its constituent elements: Sodium (Na) and Chlorine (Cl) respectively.
    Please read on Separation Techniques in Chemistry here.

  4. A pure compound will always have a fixed boiling and melting point.
    Please read the explanations on the Physical Property of Matter here.

  5. A compound is always homogenous in nature. This means that it's always composed of the same elements.
    You can read more on Homogenous and Heterogeneous Mixtures here.

  6. Heat or Light energy is always evolved or absorbed in the formation of a compound. (This is the concept of exothermic and endothermic reactions).
    You can read on the Periodic Table and Classification of Elements here.

Please click here to follow Len Academy on Google News.

Please like and follow our official facebook page here for great educational write-ups.

You can follow Len Academy on twitter here.Thank you.


Kindly share this article via the links below:


len

Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.


Please Register here or Login here to contribute to this topic by commenting in the box below.

CONTRIBUTE TO THIS TOPIC | ASK A QUESTION


Amazing facts in Chemistry

The only letters that failed to appear on the periodic table are letters:

J     &     Q

Gold and copper are the only two non-silvery colored metals.

Copper is the only metal that is naturally antibacterial. For this reason, some children utilize 'copper water bottles' in schools

Water freezes faster when it’s warm than when it’s cold

Most element in their pure state exists physically in different forms. For instance, pure carbon can exist as both diamond and graphite. This phenomenon is called allotropy

If you pour a handful of salt into a full glass of water, the water level will go down rather than overflowing the glass.

Similarly, if you mix half liter of water and half litre of alcohol, the total volume of the liquid will be les than one litre


NOTABLE POINTS IN Chemistry

In chemistry, hydrocarbons can be classified as either aliphatic or aromatic. Recently, both classifications of hydrocarbon were based on their structure rather than their origin.

Aliphatic hydrocarbons are put into three main groups according to the types of bonds they possess. These are:

  1. Alkanes

  2. Alkenes

  3. Alkynes

They are shown in the image below:

Alkanes, Alkenes and Alkynes - Len Academy

It's important to note the followings:

  • Alkanes have single bonds (only) in their structures.

  • Alkenes always have a carbon-carbon double bond present in their structure.

  • Alkynes always have a carbon-carbon triple bond present in their structure.

 

Aromatic hydrocarbons are classified into:

  • Arenes: They contain benzene ring as a structural unit. Below is the structure of a benzene ring.

Benzene Ring - Len Academy

 

  • Nonbenzenoid aromatic hydrocarbons: They possess special stability but lack a benzene ring as a structural unit.

Organic chemistry is the study of carbon and it's compounds.

Carbon is the focus of organic chemistry because it has a wide chemical diversity in the sense that it can combine with other carbon atoms to form a long chain of carbon molecule. This ability and process whereby carbon can form a long chain of itself is called catenation.

Please read the introduction to organic chemistry here

A major challenge encountered when calculating molecular mass is that it becomes difficult or impossible to calculate especially when the relative molecular mass of large molecules, polymers and macromolecules are involved.

Examples of large molecules (with indefinite molecular masses) include carbohydrates, cellulose and complex sugars.

The large molecules (above) have no specific chemical formula throughout their volume.

Please read more on carbohydrates and sugars here

Understand that Relative Molecular Mass prove to be useful only when we calculate substances with small and definite molecular sizes. This was proven through the modifications of Dalton's atomic theory.

Please read on Dalton's atomic theory and its modifications here.

Calculate the Relative Molecular Mass of methane (CH4). (Carbon=12.001 and H=1.00794)

  • Molecular Mass = Atomic mass of carbon + Atomic mass of Hydrogen

  • Methane is composed of one atom of Carbon and 4 atoms of Hydrogen.

  • 12.001 + (1.00794 x 4)

Molecular Mass of Methane = 16.033 amu

Please read more on molecular mass here


Calculate the Relative Molecular Mass of water (H2O). (Oxygen=15.9994 and Hydrogen=1.00794)

  • Molecular Mass = Atomic mass of Hydrogen + Atomic mass of Oxygen

  • Water contains 2 atoms of Hydrogen and 1 atom of oxygen.

  • (1.00794 x 2) + 15.9994

Molecular Mass of Water = 18.015 Da

Please read on emperical formula and its calculations here

Gold - Len Academy

Below are some facts about gold:

  • It is the only metal that has a gold (golden) color

  • Gold is present inside the earth crust in all the seven continents

  • Pure gold is soft and very stretchable (It can even be stretched into threads)

  • The Latin name of Gold is aurum which means 'shining dawn'. For this reason, its chemical symbol is 'Au'

  • Gold is a very good conductor of electricity. This is why it’s sometimes used in making USB and audio cables

  • Gold is non toxic and can be eaten with food. It is sometimes added to desserts in some expensive restaurants

  • The term Gold originated from an ancient English word 'geolu' which means yellow

  • 24karat gold is the purest gold element

Please read more interesting facts about gold here