Chemistry

Compounds in Chemistry: Characteristics of Compounds

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

Topics in Chemistry

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 Mixtures and Separation of Mixtures Mixtures and Separation of Mixtures - part 2 Mixtures and Separation of Mixtures - part 3


Academic Questions in Chemistry

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

The Separating Funnel is a technique used in the separation of mixtures. Another name for Separating Funnel is the _____ Funnel.

  • A. Partition
  • B. Separatory
  • C. Division
  • D. Liquid
  • E. Half
  • F. Dividing

2NH4+(aq) + Ag+(aq) -> 2H4AgN

The equation above represents _____ acid.

  • A. Svante Arrhenius'

  • B. Brønsted–Lowry's

  • C. Gilbert Lewis'

  • D. Avogadro's

  • E. Sir Isaac Newton's

  • F. Albert Einstein's

According to Brønsted Thomas Martin Lowry, an acid is defined as _____.

  • A. Any substance that produces hydrogen ion (H+) when dissolved in water

  • B. A substance that accepts electron pair in a chemical reaction

  • C. A substance that gives out hydronium ion (H3O+) when dissolved in water

  • D. A substance that donates a proton in a chemical reaction

  • E. A substance that reacts with a base to form salt and water

  • F. A substance whose hydrogen ions  (H+) are displaced after a reaction with metals higher in the activity, reactivity or electrochemical series

Which of the following is NOT a characteristic of chemical change?

  • A. A new thing is formed
  • B. It cannot be easily separated into it's constituents elements
  • C. A new chemical formula accompanies whatever is formed
  • D. The burning of candle is an example of a chemical change
  • E. Blood is an example of a chemical change
  • F. Iron rust is an example of a chemical change

Which of the following statement is FALSE concerning a physical change _____.

  • A. Substances formed in a physical change have a unique chemical formula and IUPAC name
  • B. It's a change that is easily reversible
  • C. It's a change that can be separated via an appropriate separation technique
  • D. No new substance is formed
  • E. A mixture of salt and water is a physical change
  • F. Physical change can result to a change in color and shapes of substances

The following substances will sublime EXCEPT _____.

  • A. Sodium Cryolite
  • B. Solid Carbon(IV)oxide
  • C. Arsenic
  • D. Sulphur
  • E. Iodine Crystals
  • F. Naphthalene

Which of the following is a state of matter?

  • A. Ions
  • B. Plasma
  • C. Compounds
  • D. Molecules
  • E. Atoms
  • F. None of the above

The ideal way of separating a mixture of blood is through _____.

  • A. Chromatography
  • B. Fractional Distillation
  • C. Centrifugation
  • D. Filtration
  • E. Separating Funnel
  • F. Fractional Crystallization

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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.

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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.


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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.

Please read some interesting facts about gold here

Copper is the only metal that is naturally antibacterial. This is why you would see some children utilize 'copper' water bottles in schools

Water actually 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.

Please read on modification of Dalton's atomic theory here.

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