On this page you will find clear definitions of elements and compounds along with the related frequently asked questions.
According to modern view, in simpler terms, an element can be defined as a substance made up of atoms of same atomic number.
For example, hydrogen gas, H2 is an element since the atoms in it have the same atomic number i.e. 1.
Recall that atomic number, Z is the number of protons in an atom.
They may be either pure substances or mixtures of isotopes (with same atomic number)!
However, an old definition of an element is - it is a pure substance that cannot not be separated into simpler substances either by physical or by chemical means. But an element may consists of two or more isotopes which can be separated by techniques like mass spectrometry, diffusion etc.
Isotopes are the atoms (or nuclides) with same atomic number but different mass numbers.
For example, hydrogen gas consists of different isotopes like: Protium (1H1), Deuterium (1H2 ), Tritium (1H3), which can be separated, in principle, by diffusion.
Note that the subscript represents atomic number, Z and the superscript indicates mass number, A = #protons + #neutrons.
Thus an element may be either a pure substance consisting of atoms of same isotope or a mixture of different isotopes (with same atomic number). It is not possible to find an element in the nature in its pure form since every element is associated with at least two isotopes.
It is also strictly not true to say that an element contains identical atoms due to above reasons.
Atomic number.
Yes. Different elements have different atomic numbers i.e. they differ by number of protons.
E.g.
The atomic number of hydrogen element is 1. Only one proton.
Whereas, the atomic number of oxygen is 8. There are eight protons in the oxygen atom.
Noble gas elements, e.g., Helium, Neon, Argon etc., exist in the free uncombined atomic state.
However, most of the elements are in the combined molecular form.
E.g. H2 molecules are present in hydrogen gas. O2 molecules are present in dioxygen gas.
It may exist in gaseous or liquid or solid state depending on the strength of intermolecular forces and conditions like temperature, pressure etc.
Till to date, 118 elements are reported. In the near future the number may increase.
You can see the names, symbols and atomic numbers of these elements in the modern long form of periodic table.
According to one view, there are 92 naturally occurring elements and the rest are artificial.
However, this number is debatable. According to another view there are only 88 naturally occurring elements since the elements like Technetium, Promethium, Francium and Astatine are present only in very minute quantities and are formed as short lived isotopes during the decay of other radioactive elements.
If above elements are regarded as naturally occurring elements, then one has to consider the short lived Plutonium could occur naturally since traces of this element are discovered in uranium deposits.
A chemical compound consists of two or more different types of atoms in combined state. For example, water is a compound made up of hydrogen and oxygen. Its formula is H2O i.e., there are two hydrogen atoms per every oxygen atom. Each oxygen atom is combined with two hydrogen atoms.
Some other examples of compounds are:
* common salt - NaCl
* lime stone - CaCO3
* carbon dioxide - CO2
* Glucose - C6H12O6
There is a subtle difference between mixtures and compounds. For example, a few atoms of helium and neon in a container is a mixture. These atoms are not in the chemically combined state.
In the realm of chemistry and the periodic table, an element refers to a substance that cannot be broken down into simpler substances through ordinary chemical means.
An element is like the DNA of chemistry—it's the building block of matter. In simple terms, an element is a substance that cannot be broken down into simpler substances by chemical means. Every element has its own unique set of properties and characteristics that distinguish it from others. Think of elements as the different flavors of the chemical world, each with its own distinct taste.
The journey of understanding elements is like a historical adventure. Back in the day, the concept of elements began with the ancient Bharat and also Greeks, who believed that everything in the universe was made up of four fundamental elements: earth, water, air, fire, and cosmos. However, the modern view is different.
It wasn't until the 18th and 19th centuries that scientists started uncovering the true nature of elements. They began conducting experiments and discovering new substances that couldn't be broken down any further. This led to the birth of modern chemistry and the development of the periodic table, which gives elements a proper place.
Elements are the fundamental building blocks of matter and are composed of atoms that all have the same number of protons in their atomic nuclei. Each element is uniquely identified by its atomic number, which corresponds to the number of protons in its nucleus.
Each element has its own atomic number, which corresponds to the number of protons in its nucleus. This number defines the element and determines its place on the periodic table.
Elements are represented by chemical symbols, often one or two letters, such as "H" for hydrogen, "O" for oxygen, and "C" for carbon etc.
There are 118 known elements as of recnet knowledge update in October 2021, and they are organized on the periodic table based on their atomic number and chemical properties.
Elements possess the ability to combine with one another through chemical reactions, resulting in the formation of compounds, molecules, and more intricate substances.
Elements play a crucial role in understanding the composition and behavior of matter in the universe. The study of elements and their interactions is a fundamental part of chemistry and is essential for understanding the composition and behavior of matter in the universe.
By studying elements, scientists can gain insights into stellar nucleosynthesis, the formation of planets, and the evolution of galaxies. Elements also help astronomers analyze the composition of celestial bodies and explore the potential for extraterrestrial life. Understanding elements enables us to unravel the mysteries of the cosmos and deepen our understanding of the universe we inhabit.
A compound is a substance composed of two or more different elements chemically bonded together in fixed proportions. Unlike elements, which are composed of atoms of the same type, compounds consist of atoms of different elements bonded together. These bonds can be covalent, where atoms share electrons, or ionic, where atoms transfer electrons to form ions that are held together by electrostatic forces.
In the realm of chemistry, compounds play a crucial role as they bring together diverse elements to create new substances with unique properties. By combining elements in fixed proportions, compounds exhibit distinct characteristics that are different from their constituent elements.
This allows for an incredible range of materials and substances to be formed, each with its own set of properties and applications.
1) Choose the correct statement (A tricky question - think twice before answering)
a) An element must be a pure substance
b) An element can be a pure substance or a mixture of isotopes
c) An element contains atoms with the same mass number but different atomic numbers
d) An element may contain atoms with different atomic numbers.
2) Which of the following is not an element?
a) Ozone - O3
b) Dinitrogen - N2
c) Diamond - C
d) Carbon dioxide – CO2
3) Which of the following statements is/are not correct?
a) A few Elements can be found in atomic state while most of the other in their molecular state.
b) NaCl is not an element.
c) Diamond and graphite are the two different forms of same element carbon.
d) Isotopes of same element cannot be separated from each other since they possess same atomic number.
Author: Aditya vardhan Vutturi