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 → Elements, Compounds, and Mixtures ↓


Introduction to the Periodic Table


The periodic table is a chart that arranges all known chemical elements in a systematic way. It was created to provide a useful framework for understanding the chemical behavior of the elements. Each element on the periodic table is unique and has specific properties that distinguish it from other elements.

Structure of the Periodic Table

The periodic table is arranged in rows and columns. The rows are called periods and the columns are called groups or families. The horizontal rows (periods) are numbered from 1 to 7. This number tells us the number of electron shells in the atoms of the element. The vertical columns (groups) are numbered from 1 to 18 and tell us the number of electrons in the outer shell of the atoms of the element.

H2O
by Lee B. BCNOF
NaMgAlSiPsClAr
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br K
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po Et Rn
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og

Group

Elements in the same group tend to have similar properties. For example, Group 1, known as the alkali metals, are all highly reactive and have one electron in their outer shell. Some elements in this group include lithium (Li), sodium (Na), and potassium (K).

Group 1: Alkali Metals
- Li: Lithium
- Na: sodium
- K: potassium

Period

As you move across a period from left to right, the atomic number of elements increases. This means that each element has one more proton in its nucleus and one more electron in its orbitals than the element before it. Periods help indicate the number of energy levels in an atom.

Recognizing the elements and their symbols

Each element in the periodic table is represented by a unique one or two letter symbol called a chemical symbol. For example:

  • H for hydrogen
  • O means oxygen
  • Na for sodium

These symbols are used internationally, which means that a chemist sitting anywhere in the world will be able to understand these symbols.

Metals, nonmetals and metalloids

The periodic table also helps differentiate elements as metals, nonmetals, and metalloids:

  • Metals are found on the left and in the middle of the periodic table. They are usually shiny, good conductors of electricity and heat, and malleable.
  • Nonmetals are found on the right side of the table (except hydrogen). They are usually not shiny and are poor conductors of electricity and heat.
  • Metalloids have properties of both metals and nonmetals and are found between metalloids and nonmetals in the table.

Chemical formula

Chemical formulas are a way of showing the elements that make up a compound. They use symbols from the periodic table. For example, water is made up of two hydrogen atoms and one oxygen atom, written as H 2 O

Examples of chemical formulas:
- NaCl: sodium chloride (table salt)
- CO 2 : Carbon dioxide
- C 6 H 12 O 6 : Glucose

Compounds and mixtures

When different elements combine, they form compounds or mixtures:

  • Compounds are substances that contain two or more different elements bonded together in a specific way.
  • A mixture is a combination of two or more substances, where each substance retains its chemical identity.

The elements in a compound always exist in fixed proportions. For example, in water (H 2 O), there are always two hydrogen atoms for every one oxygen atom. However, the proportions of substances in a mixture can vary. For example, in a salad, you may have different amounts of lettuce, tomatoes, and cucumbers.

Importance of Periodic Table

The periodic table is important in chemistry because it provides a lot of information about the elements, their relationships, and their properties. It helps chemists understand how the elements interact with each other and predict what might happen when different elements are combined.

Understanding atomic number and mass number

The atomic number of an element is the number of protons in its nucleus. It is different for each element. For example, hydrogen has an atomic number of 1, which means it has one proton in its nucleus.

The mass number is the sum of the protons and neutrons in the nucleus of an atom. It can be used to distinguish between isotopes, which are atoms of the same element that have different numbers of neutrons.

Visual example of the representation of an element

H Hydrogen 1 1.008

In the above example, the symbol H represents hydrogen, which has atomic number 1 and an average atomic mass of about 1.008 amu (atomic mass units).

Conclusion

The periodic table is an indispensable tool in chemistry, providing information about the properties and behaviors of all known elements. Understanding its structure is essential for anyone studying chemistry, as it simplifies complex information about what atoms are made of and how they interact with each other.


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Introduction to the Periodic Table

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