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Uncover the Secrets of Atomic Structure
Embark on a journey through the microscopic world of atoms. Our expert-led video lessons break down complex concepts, helping you visualize and understand the foundation of chemistry and physics.

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Now Playing:Structure of the atom – Example 0a
Intros
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  1. Introduction to atomic structure
  2. Introduction to atomic structure
    Inside an atom.
  3. Introduction to atomic structure
    The particles that make an atom
Examples
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  1. Use information on elements in the Periodic Table to identify the number sub-atomic particles in elements.
    Find the number of protons, neutrons and electrons in an atom of the following elements:
    1. i) Nitrogen
      ii) Silicon

    2. i) Calcium
      ii) Aluminum

Atomic structure
Jump to:NotesConceptFAQsPrerequisites
Notes
In this lesson, we will learn:
• The definition of an atom.
• The particles that make up an atom and where in the atom they are found.
• The charge and mass of an atom's constituent particles.

Notes:

• The atom is the smallest indivisible unit of matter, comprised of protons, neutrons and electrons.

• It's known as the smallest indivisible unit of matter because an atom is the smallest unit of a material that still shows all the properties of the bulk material. It is also the smallest unit of matter that is stable in its own right.

• Atoms are comprised of three main particles – protons and neutrons, which make up the central core of the atom known as the nucleus, and electrons, which are found in shells (or orbitals) occupying space outside the nucleus.

• A brief overview of the particle properties is below:

overview of the particle properties


• The nucleus contains almost all of the mass of an atom as it contains protons and neutrons, which both have a relative mass of 1 AMU. The nucleus also has an overall positive charge, as neutrons have no charge and protons have a relative charge of +1.

• The mass of an electron is (relative to protons and neutrons) so small that it is often ignored; it is around 1/1840 AMU. An electron has a relative charge of -1 so an electron has an equal but opposite charge to a proton.

• In an atom of an element, the number of protons is always equal to the number of electrons. This means the overall charge of an atom is zero and is therefore neutral.

• Because the atomic mass of an electron is approximately 0, we can say that the atomic mass, or mass number, of an element tells us the number of protons and neutrons in an atom because only these two particles contribute to the mass of the atom.

• Using the last two points of information, we can look at the periodic table and predict the number of protons, electrons and neutrons in an atom of any element!

Concept

Introduction to Atomic Structure

Welcome to our exploration of atomic structure! Let's dive into the fascinating world of atoms, the building blocks of everything around us. To kick things off, we've prepared an introduction video that will give you a solid foundation in understanding these tiny particles. This video is a great starting point, as it breaks down complex concepts into easy-to-grasp visuals and explanations. As we progress, you'll learn about the components of an atom, including protons, neutrons, and electrons, and how they interact to form different elements. We'll also discuss the arrangement of these particles within the atom and how this affects an element's properties. By the end of this section, you'll have a clear picture of atomic structure and be ready to tackle more advanced topics. Remember, understanding atoms is key to unlocking the secrets of chemistry and physics!

FAQs

  1. What is an atom?

    An atom is the smallest unit of matter that retains the properties of an element. It consists of a nucleus containing protons and neutrons, surrounded by electrons orbiting in energy levels. Atoms are the building blocks of all matter in the universe.

  2. How do we determine the number of protons, neutrons, and electrons in an atom?

    The number of protons is equal to the atomic number, which is found on the periodic table. In a neutral atom, the number of electrons equals the number of protons. To find the number of neutrons, subtract the atomic number from the rounded atomic mass.

  3. What is the difference between atomic number and atomic mass?

    The atomic number is the number of protons in an atom's nucleus and determines the element's identity. The atomic mass is the total number of protons and neutrons in the nucleus. It's usually given as an average due to the existence of isotopes.

  4. Why are atoms typically neutral?

    Atoms are typically neutral because the number of positively charged protons in the nucleus is balanced by an equal number of negatively charged electrons orbiting the nucleus. This balance results in a net charge of zero for the atom.

  5. How does the arrangement of electrons affect an atom's properties?

    The arrangement of electrons, especially in the outermost shell (valence electrons), determines an atom's chemical properties and how it interacts with other atoms. This arrangement influences bonding behavior, reactivity, and many physical properties of elements and compounds.

Prerequisites

Understanding atomic structure is a fundamental concept in chemistry, but to fully grasp its intricacies, it's crucial to have a solid foundation in certain prerequisite topics. One of the most important prerequisites is the history and development of the periodic table. This topic provides essential context for comprehending atomic structure and its significance in the field of chemistry.

The periodic table is not just a chart of elements; it's a roadmap to understanding atomic structure. By delving into its history and development, students gain insights into how scientists gradually uncovered the secrets of atoms. This knowledge serves as a crucial stepping stone to grasping the complexities of atomic structure.

When studying the periodic table's evolution, students learn about early attempts to organize elements based on their properties. This historical perspective helps in understanding why atoms of different elements behave differently, which is directly related to their atomic structure. The periodic table's arrangement reflects the electron configuration of atoms, a key aspect of atomic structure.

Moreover, the development of the periodic table coincides with major discoveries about atomic structure. For instance, the discovery of subatomic particles like electrons, protons, and neutrons played a crucial role in refining the periodic table. Understanding this historical progression helps students connect the dots between the table's organization and the structure of atoms.

The periodic table also introduces the concept of atomic number, which is fundamental to atomic structure. By studying how Mendeleev and others arranged elements, students begin to grasp the importance of proton number in determining an element's identity and properties. This directly ties into understanding the nucleus of an atom and its composition.

Furthermore, the periodic trends observed in the table, such as atomic size and ionization energy, are direct consequences of atomic structure. By studying how these trends were discovered and incorporated into the periodic table, students gain a deeper appreciation for the intricacies of electron shells and energy levels within atoms.

In conclusion, the history and development of the periodic table serves as an invaluable prerequisite for understanding atomic structure. It provides the necessary background, introduces key concepts, and helps students visualize the abstract nature of atoms. By mastering this prerequisite topic, students are better equipped to tackle the complexities of atomic structure, making their journey through chemistry more coherent and engaging.