Topics in Chemistry
Chemistry Scheme of Work, SS1 Third Term Chemical Industries: Petrochemicals, Biodegradable, Non-biodegradable Wastes and Pollutants Chemical Industries: Types, Advantages, Disadvantages and Factors affecting Chemical Industries Hydrocarbons: Fractional Distillation of Crude oil and Uses of its Fractions Hydrocarbons: Sources, Classification and Test for Saturated and Unsaturated Hydrocarbons Trioxocarbonates: Preparation, Physical and Chemical Properties, Tests and Uses of Trioxocarbonates Carbon and its Compounds: Oxides of Carbon, Carbon(IV) oxide Carbon and its Compounds: Oxides of Carbon Amorphous Allotropes of Carbon Carbon: Structure and Allotropes of Carbon Salts in Chemistry: Types, Properties, and Uses of Salts Salts in Chemistry, their Classifications, Solubility, Preparations and Colors pH Indicators, Types of Indicators and Importance of pH and pOH Relative Acidity and Alkalinity (pH Scale), and Calculations on pH Bases and Alkalis: Definitions, Classification, Physical and Chemical Properties Bases: Preparation of Bases and Alkalis, Test and Uses Physical and Chemical Properties of Acids, Preparation, Test and Uses of Acids. Acid: Definition, Basicity, and Types of Acid Families of elements in the periodic table Periodic table and Classification of ElementsAcademic Questions in Chemistry
With regards to redox reactions, which of the following statement is wrong?
A. Redox reaction are examples of chemical change
B. Reduction is the gain of electron
C. Substances that donates election during chemical reaction are termed reductants
D. Oxidizing agents are always reduced in chemical reactions
E. Oxidation occurs at the cathode in electrolysis
F. Hydrogen is a reducing agent
In chemistry, physical change is associated only with the rearrangement of molecules while the internal composition of the substance remains the same.
A. True
B. False
_____ electron(s) is a term that describes the number of electron(s) in the outermost shell of an atom.
A. Outer
B. Excess
C. Valence
D. Positive
E. Negative
F. Last
_____ is the negative electrode in electrolysis.
A. Anode
B. Anion
C. Cathode
D. Cation
E. Ion
F. Electrolyte
The above diagram shows the _____ type of bond.
A. Covalent
B. Polar covalent
C. Coordinate covalent
D. Metallic
E. Van dear walls
F. Ionic
Metals are referred to as _____ in their impure state.
A. Diluted
B. Consecrated
C. Coloured
D. Ores
E. Stained
F. Strained
Metals generally have the quality to shine, glow, sparkle, glitter, reflect light and be polished. This characteristic of metals is termed _____.
A. State
B. Ductility
C. Luster
D. Malleability
E. Hardness
F. Inflorescence
The _____ spectrometry experiment conducted on isotopic elements gave a confirmation for the existence of isotopes.
A. Mole
B. Volume
C. Weight
D. Number of moles
E. Mass
F. Amount of substance
Nuclear chemistry is a branch of chemistry that deals with the chemical and physical properties of radioactive elements and their compounds, as well as the study of the chemical effects associated with the emission of radiation.
This field intersects with various domains, including chemistry, physics, geology, medicine, and environmental science, revealing its multifaceted nature.
With the growing interest in sustainable energy and nuclear medicine, the importance of nuclear chemistry has surged among researchers.
Recall that atoms are comprised of protons, neutrons, and electrons. However, nuclear chemistry is an aspect of chemistry that focuses on the nuclei of atoms. Meanwhile, present in the nuclei of atoms are protons and neutrons respectively.
You can read on periodic table and characteristic of elements here.
At the heart of nuclear chemistry is radioactivity, which is the spontaneous disintegration of unstable atomic nuclei, resulting in the emission of particles and energy.
Simply put, radioactivity refers to the spontaneous (natural and sudden) emission of radiation, particles and energy by a radioactive element through the breakdown of its nucleus. This process which is brought about by the spontaneous disintegration of unstable atomic nuclei may also be termed as radioactive decay.
You can read on dynamic equilibrium in chemistry here.
An undersatanding on the characteristics of radioactivity will aid us to properly comprehend this field of nuclear chemistry.
Below are the characteristics of radioactivity:
Radioactive elements spontaneously and continually emit radiation.
Large amounts of energy accompanies the release of these radiation.
The radiation can pass through opaque objects.
This radiation results into the ionization of gasses whenever it passes through them.
The radiation emitted by radioactive elements are neither affected by temperature nor pressure.
The radiation affects photographic plates.
It may cause certain substance to fluoresce or glow.
Alpha particles, beta particles and gamma rays may be spontaneously emitted from the nuclei of radioactive elements.
You can attempt questions and answers in chemistry here.
There are three primary types of radiation emitted by radioactive elements. These are:
Alpha particles
Beta particles
Gamma rays
Each of these radiation types have got its distinct properties and implications for both chemistry and health.
Please read on the characteristics of alpha particles, beta particles and gamma rays here.
The study of nuclear chemistry involves understanding not only the nature of radioactive decay, but also the pathways through which these reactions occur. In this regard, the rate of decay is characterized by the half-life; which is the time required for half of a sample of a radioactive substance to decay.
The half-life of a radioactive element (or isotope) is the amount of time it takes for 50℅ (or one-half) of the radioactive isotope to decay.
Understand that the half-life of a specific radioactive isotope does not change; and as a result, is unaffected by temperature or pressure. Also, the half-life of a radioactive isotope does not depend on of the initial amount of that isotope.
You can read on rate of chemical reaction here.
Different isotopes possess different half-lives, which can range from fractions of a second to billions of years. This fundamental concept is crucial for applications in dating archeological findings, such as carbon dating, to determine the age of ancient organisms and artifacts based on their carbon isotopes.
The table below shows various radioactive elements, their stable isotopes, alongside their half-life.
| Elements | Most Stable Isotope | Half-Life |
| Uranium | U-238 | 4,470,000,000 years |
| Plutonium | Pu-244 | 80,000,000 years |
| Technetium | Tc-91 | 4,210,000 years |
| Curium | Cm-247 | 15,600,000 |
| Neptunium | Np-237 | 2,140,000 years |
| Thorium | Th-229 | 75,400 years |
| Protactinium | Pa-231 | 32,800 years |
| Americium | Am-243 | 7370 years |
| Radium | Ra-226 | 1600 years |
| Berkelium | Bk-247 | 1380 years |
| Californium | Cf-251 | 898 years |
| Polonium | Po-209 | 102 years |
| Actinium | Ac-227 | 21.77 years |
| Promethium | Pm-145 | 17.4 years |
| Einsteinium | Es-252 | 471.7 days |
| Fermium | Fm-257 | 100.5 days |
| Mendelevium | Md-258 | 51.5 days |
| Radon | Rn-222 | 3.82 days |
| Dubnium | Db-268 | 32 hours |
| Rutherfordium | Rf-265 | 13 hours |
| Lawrencium | Lr-262 | 4 hours |
| Nobelium | No-259 | 58 minutes |
| Francium | Fr-223 | 22 minutes |
| Seaborgium | Sg-271 | 2.4 minutes |
| Copernicium | Cn-285 | 29 seconds |
| Roentgenium | Rg-281 | 26 seconds |
| Bohrium | Bh-267 | 17 seconds |
| Darmstadtium | Ds-281 | 11.1 seconds |
| Hassium | Hs-269 | 9.7 seconds |
| Flerovium | Fl-289 | 2.65 seconds |
| Meitnerium | Mt-276 | 0.72 seconds |
| Moscovium | Mc-289 | 87 milliseconds |
| Livermorium | Lv-293 | 61 milliseconds |
| Oganesson | Og-294 | 1.8 milliseconds |
| Tennessine | Unknown |
You can read on Avogadro's number explained with worked examples here.
In the realm of practical applications, nuclear chemistry plays a vital role in various sectors, especially in energy production and healthcare. The field has contributed to the development of nuclear reactors, which provide a significant portion of the world’s electricity.
Nuclear fission, the process by which atomic nuclei split to release energy, is harnessed in nuclear power plants. Effective control of this process requires a deep understanding of nuclear chemistry principles to ensure safety and efficiency.
Moreover, nuclear chemistry is instrumental in medicine, specifically in the field of nuclear medicine. Radiopharmaceuticals, substances that emit radiation, are used for both diagnosis and treatment. Also, techniques such as Positron Emission Tomography (PET) scans and cancer therapies utilizing radioactive isotopes are potent examples of how nuclear chemistry can enhance patient outcomes.
Please read more on the advantages and disadvantages of nuclear chemistry here.
Unfortunately, nuclear chemistry does pose risks, particularly related to radiation exposure. Proper safety protocols and regulations are essential to mitigate health hazards.
The study of the environmental impact of radioactive materials, as well as the development of waste disposal methods for radioactive substances, is an ongoing area of research crucial for sustainable practices.
You can read on the concept of ions and electrolysis here.
In conclusion, nuclear chemistry and radioactivity are vital fields offering insights into the fundamental processes that govern atomic interactions and energy transformations.
As we continue to explore and harness the potential of nuclear chemistry for energy and medical applications, it is imperative to address the associated challenges responsibly.
For academicians, engaging with these topics opens avenues for groundbreaking research and innovation, with the potential to shape a sustainable future.
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Amazing facts in Chemistry
Plastic and Glass can decompose, but not in our lifetimes. It takes an average time of 450 years for plastics to decompose. As for the decomposition of glasses, it takes about 4,000 years
The only letters that failed to appear on the periodic table are letters:
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
Below are the physical properties of metals:
They exist in solid state.
The have high densities.
They are good conductors of heat and electricity.
The have the ability to be polished, to glow, sparkle and reflect light.
They can be bent, flattened and made into sheets called foils.
They can be drawn into wires.
Iron undergoes magnetism while most metals are poorly magnetized.
They typical have high melting point.
They generally have high boiling point.
With the exception of lithium, sodium and potassium, most metals are generally hard.
They have the ability to make sound when in contact with other objects or metals.
Please read details on the physical properties of metals here
John Dalton is an English chemist who brought clarity into the composition of matter and the basis for their chemical reactions.
Below are Dalton's Atomic Theory:
All matter consists of tiny indivisible particles called atoms.
Atoms of the same element are identical to each other in every aspect because they have the same shape and mass, while atoms of different elements are different in all respect.
Atoms are indestructible and can neither be created nor destroyed.
Atoms of different elements can combine with each other in simple whole number ratios to form compounds.
Atoms of the same element share similar physical and chemical properties. They can also combine in more than one ratio to form two or more compounds.
Meanwhile, understand that the above theories of John Dalton had been modified.
Please read on Dalton's atomic theory and its modifications here
The periodic table, also called periodic table of elements or Mendeleev's table, is a table that shows an organized arrangement of the 118 chemical elements according to their atomic number.
Out of the 118 elements; elements 1 - 94 are present in nature while elements 95 - 118 are synthesized artificially.
The manner at which elements are arranged on this table reveals some similarities in their electronic configurations and chemical properties.
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)
Step 1: Identify the given parameter from the question.
Fe = 69.94%, O = 30.06%.
Empirical formula = Fe?O?
Step 2: Convert the percentages to gram. (just attribute grams to the %).
Step 3: To get the mole ratio of each element, convert the gram to moles using the formula (mole = mass/molarmass). Please merorize this formula because we always work with moles in emperical formula.
Mole of Fe: 69.94/55.85 = 1.252mol
Mole of O: 30.06/16 = 1.879mol
Step 4: Divide both sides by the smallest mole ratio.
Iron has the smallest mole ratio in our case, therefore: 1.252/1.252 = 1, 1.879/1.252 = 1.5
We now have the formula = Fe1O1.5
Step 5: Multiply each of the moles by the smallest whole number that will convert each into a whole number. (In our case, the number '2' is the smallest whole number that will make '1.5' and '1' whole numbers when multiplied by it.
For iron (Fe), we will have 1 x 2 = 2
For oxygen (O), we will have 1.5 x 2 = 3
Step 6: Write the empirical formula.
The empirical formula= Fe2O3
Iron(III)tetraoxosulphate(VI)
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:
Alkanes
Alkenes
Alkynes
They are shown in the image below:
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:
