Grade 7
  1. Introduction to Chemistry  1.1. What is Chemistry?  1.2. Importance of chemistry in daily life  1.3. Branches of chemistry  1.4. Scientific Method in Chemistry  1.5. Laboratory Safety Rules and Precautions  1.6. Common Laboratory Equipment and Their Uses  1.7. Units of measurement in chemistry
  2. Matter and its properties  2.1. Definition of Matter  2.2. Classification of matter  2.3. Properties of matter  2.3.1. Physical properties  2.3.2. Chemical properties  2.4. States of matter  2.4.1. Solid state  2.4.2. Fluid state  2.4.3. Gaseous state  2.4.4. Plasma and Bose–Einstein condensates  2.5. Changes in the states of matter  2.5.1. Melting and freezing  2.5.2. Evaporation and Condensation  2.5.3. Sublimation and deposition  2.6. Density and its applications  2.7. Diffusion and its importance
  3. Elements, Compounds, and Mixtures  3.1. Definition of the element  3.2. Classification of elements  3.3. Metals, Nonmetals and Metalloids  3.4. Noble gases and their properties  3.5. Introduction to the Periodic Table  3.6. Definition of Compound  3.7. Properties of Compounds  3.8. Introduction to Chemical Formulas  3.9. Definition of Mixture  3.10. Types of mixtures  3.10.1. Homogeneous mixture  3.10.2. Heterogeneous mixtures  3.11. Difference Between Compounds and Mixtures  3.12. Solutions, Colloids and Suspensions
  4. Separation of mixtures  4.1. Need for separation of mixtures  4.2. Separation methods  4.2.1. Filtration  4.2.2. Sedimentation and decantation  4.2.3. Evaporation  4.2.4. Crystallization  4.2.5. Distillation  4.2.6. Chromatography  4.2.7. Magnetic Separation  4.2.8. Centrifugation
  5. Atomic Structure  5.1. Introduction to Atoms  5.2. Structure of the atom  5.2.1. Nucleus and electron cloud  5.3. Subatomic particles  5.3.1. Proton  5.3.2. Neutron  5.3.3. Electrons  5.4. Atomic number and mass number  5.5. Isotopes and their uses  5.6. Ions and ion formation
  6. Periodic table  6.1. Introduction to the Periodic Table  6.2. Groups and periods  6.3. Trends in the Periodic Table  6.3.1. Atomic Size  6.3.2. Metallic and non-metallic character  6.3.3. Electronegativity  6.3.4. Reactivity of the elements  6.4. Alkali metals and their properties
  7. Chemical bond  7.1. Why do atoms form bonds?  7.2. Types of chemical bonds  7.2.1. Ionic bond  7.2.2. Covalent bond  7.2.3. Metal Bond  7.3. Properties of Ionic and Covalent Compounds  7.4. Intermolecular forces
  8. Chemical reactions  8.1. Introduction to Chemical Reactions  8.2. Signs of a chemical reaction  8.3. Types of Chemical Reactions  8.3.1. Combination Reactions  8.3.2. Decomposition reactions  8.3.3. Displacement reactions  8.3.4. Double displacement reactions  8.3.5. Combustion reactions  8.4. Law of conservation of mass  8.5. Balancing simple chemical equations
  9. Acids, Bases and Salts  9.1. Definition of Acid and Base  9.2. Properties of Acids  9.3. Properties of bases  9.4. pH Scale and Indicators  9.5. Neutralization reactions  9.6. Common Acids and Bases in Everyday Life  9.7. Preparation and use of salts  9.8. Strong and weak acids and bases
  10. Solutions and Solubility  10.1. Definition of Solution  10.2. Components of the solution  10.2.1. Solvent  10.2.2. solute  10.3. Factors Affecting Solubility  10.4. Concentration of solutions  10.5. Saturated and unsaturated solutions  10.6. Colloids and suspensions  10.7. Solubility curve and its interpretation
  11. Air and atmosphere  11.1. Composition of air  11.2. Properties of gases in the air  11.3. Importance of Oxygen and Carbon Dioxide  11.4. Air pollution and its effects  11.5. Greenhouse effect and global warming  11.6. Ways to reduce air pollution  11.7. Ozone layer and its importance
  12. Water and its importance  12.1. Properties of Water  12.2. Water as the universal solvent  12.3. Importance of water for life  12.4. Water pollution and its effects  12.5. Water Purification  12.5.1. Filtration  12.5.2. boil  12.5.3. Chlorination in water purification  12.5.4. reverse osmosis  12.6. Hard and soft water  12.7. Water cycle and its importance
  13. Fuel and energy  13.1. Types of fuel  13.1.1. Fossil fuels  13.1.2. Renewable energy sources  13.2. Combustion and energy release  13.3. Global warming and its effects  13.4. Alternative sources of energy  13.5. Ways to conserve energy
  14. Metals and Nonmetals  14.1. Physical and chemical properties of metals  14.2. Physical and Chemical Properties of Non-Metals  14.3. Difference Between Metals and Nonmetals  14.4. Uses of metals and nonmetals  14.5. Corrosion of metals and its prevention  14.6. Alloys and their importance
  15. Plastics and polymers  15.1. Natural and synthetic polymers  15.2. Properties of plastics  15.3. Biodegradable and Non-Biodegradable Plastics  15.4. Environmental impact of plastic  15.5. Recycling and waste management in plastics and polymers  15.6. Daily Uses of Polymers
  16. Introduction to Organic Chemistry  16.1. Basic definitions of organic chemistry  16.2. Carbon Compounds in Daily Life  16.3. Hydrocarbons  16.4. Simple functional groups (alcohols and carboxylic acids)  16.5. Importance of organic compounds in industry

Grade 7 → Atomic Structure ↓


Ions and ion formation


When learning about chemistry and atomic structure, one of the essential topics to understand is ions and how they are formed. This explanation will cover ion formation in great detail, which will provide clarity for those new to this topic, especially students and beginners. Let's start by breaking down some basic atomic concepts before diving into ions and their formation.

Basic understanding of atoms

An atom is the smallest unit of matter that retains the properties of an element. An atom consists of a nucleus, which contains protons and neutrons, and electrons that orbit the nucleus. Protons are positively charged, electrons are negatively charged, and neutrons have no charge.

Here's a simple visual representation of an atom:

In this 2D illustration, the center black circle represents the nucleus, while the smaller red circles around it represent the electrons orbiting the nucleus. Remember, this is a simplified diagram to help you visualize the basic atomic structure.

What are ions?

Ions are atoms or molecules that have gained or lost one or more of their electrons. This gain or loss results in a net electrical charge. If an atom has more protons than electrons, it carries a positive charge and is called a cation. Conversely, if it has more electrons than protons, it carries a negative charge and is called an anion.

How do atoms become ions?

To further understand ion formation, we need to figure out what causes atoms to gain or lose electrons. Generally, atoms gain more stable electron configurations. Most atoms are stable when they have eight electrons in their outermost shell, known as the octet rule.

Cation: Positive ion

An atom can become a cation by losing one or more electrons. When this happens, the atom has more positively charged protons than negatively charged electrons. Consider sodium (Na), a common example of cation formation. Sodium has one electron in its outermost shell. By losing this electron, sodium achieves a stable arrangement:

    Sodium atom: Na 
    Electron Configuration: 2, 8, 1
    After losing 1 electron:
    Sodium ion: Na +
    Electron Configuration: 2, 8

The sodium ion now carries a positive charge (+1), because it has one less electron than the proton.

Visualizing the cation

No

In this example, we show sodium (Na) before it loses its outer electron, with two red circles around it. After it loses one electron, one red circle will be removed.

Anion: Negative ion

Anions are formed when atoms gain electrons. This gain results in having more electrons than protons, creating a negative charge. Consider chlorine (Cl) as an example of anion formation. Chlorine has seven electrons in its outermost shell. By gaining one electron, chlorine achieves a stable arrangement:

    Chlorine atom: Cl
    Electron Configuration: 2, 8, 7
    After gaining 1 electron:
    Chlorine ion: Cl-
    Electron Configuration: 2, 8, 8

The chlorine ion now carries a negative charge (-1) because it has one more electron than the proton.

Visualization of anion

Chlorine

This diagram shows the initial state of chlorine (Cl) with seven red electron circles. After gaining another electron, an additional circle will be added.

Summary of ion formation

Ions play a fundamental role in chemistry and biology. They arise from atoms attempting to achieve a stable electron configuration similar to the noble gases. Cations are positive ions formed by the loss of electrons, while anions are negative ions formed by gaining electrons. This process is central to many chemical reactions, including the formation of ionic compounds.

Examples of ion formation

Sodium chloride (salt)

Sodium chloride, commonly known as salt, is an example of an ionic compound that is formed by the combination of sodium and chlorine ions:

    Na + + Cl - → NaCl

Sodium donates its electron to chlorine, resulting in a positive sodium ion and a negative chlorine ion, which attract each other to form the compound NaCl.

Calcium oxide

Calcium oxide is formed as follows:

    Ca 2+ + O 2- → CaO

Calcium loses two electrons to attain a complete outer shell, and oxygen gains these electrons, resulting in a strong ionic bond between the calcium and oxygen ions.

Conclusion

Understanding ions and how they are formed is important for understanding further chemical concepts. Ions are obtained through the gain or loss of electrons, which is influenced by the desire of atoms to achieve stable electron configurations. This guide provides a fundamental understanding of ions, how to view them, and how they participate in forming compounds. With these basics, learners can move on to more complex chemical principles involving ions.


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