Chapter 3 SABIS Grade 10 Part 3
📚Lesson 12:📚 Atomic Symbols, Chemical Formulas, and Molecular Models
📚 Prerequisite Quiz:
What does the chemical formula of a molecular compound represent? A) The number of atoms in each element in the compound. B) The kind of ions present in the compound. C) The simplest ratio of atoms in the compound. D) The 3-dimensional shape of the compound.
What is the simplest formula of salt? A) NaCl B) H2O C) CO2 D) C6H12O6
Which of the following is true about particles in the solid state? A) They are closely packed and vibrate in fixed positions. B) They are far apart and in constant random motion. C) They have no fixed volume and shape. D) They can be compressed easily.
What is the purpose of molecular models? A) To represent the chemical symbols of elements. B) To visualize the 3-dimensional shape of molecules. C) To determine the simplest formula of a compound. D) To show the fixed volume and shape of gases.
What does the symbol '' represent in chemistry? A) A bond between two atoms. B) The simplest ratio of atoms in a compound. C) The number of particles in a compound. D) The 3-dimensional geometry of a molecule.
Explanation:
In this lesson, we will explore the symbols of atoms and elements, chemical formulas of compounds, and the use of molecular models to visualize molecular shapes. These concepts are fundamental in understanding the composition and structure of substances.
Atoms of different elements are represented by unique symbols. For example, the symbol for hydrogen is H, and the symbol for oxygen is O. Recognizing these symbols is important for understanding chemical formulas.
The chemical formula of a molecular compound represents the number and kind of atoms of each element in a molecule of that compound. It provides information about the composition of the compound and can be used to determine the simplest ratio of atoms in the compound.
Ionic compounds, network solids, and metals do not have molecular formulas because they are not made up of distinct molecules. Instead, they have empirical formulas that represent the kind of ions or atoms present and the simplest ratio in which they are found in the compound.
The simplest formula of a molecular compound gives the simplest ratio in which the atoms are found together. For example, the simplest formula of water (H2O) represents two hydrogen atoms and one oxygen atom in each molecule.
Naming molecular binary compounds follows specific rules. The first element in the formula is named first, using its element name. The second element is named by taking the root of the element and adding "-ide." Prefixes are used to denote the number of atoms present, except for the prefix "mono" which is not used for the first element. However, prefixes are not used when naming acidic compounds.
Chemists use '' to represent a bond between two atoms. This symbol indicates the connection between atoms in a molecule and represents the sharing or transfer of electrons.
The structural formula shows the number and kind of atoms of each element in a molecule and how atoms are bonded to each other. It provides more detailed information about the arrangement of atoms and bonds in the molecule.
Molecular models are physical models that represent molecules and help visualize their 3-dimensional shape or geometry. These models consist of balls representing atoms and sticks or springs representing bonds between atoms. They are useful tools for understanding molecular structures and properties.
Particles in the solid state are closely packed and vibrate in fixed positions, giving solids a fixed shape and volume. In contrast, particles of a gas are far apart and in constant random motion, leading to their ability to flow and be compressed.
End of Lesson Quiz:
The chemical formula of a molecular compound represents the: A) Number and kind of atoms in each molecule. B) Ratio of ions present in the compound. C) 3-dimensional shape of the compound. D) Fixed volume and shape of gases.
What is the purpose of the structural formula? A) To represent the symbols of atoms and elements. B) To determine the simplest formula of a compound. C) To visualize the 3-dimensional shape of molecules. D) To show the constant random motion of particles in gases.
Which compounds are not made up of distinct molecules? A) Molecular compounds. B) Ionic compounds. C) Network solids. D) Gases.
How can the simplest formula of a molecular compound be deduced from its chemical formula? A) By counting the number of atoms in each element. B) By determining the 3-dimensional shape of the compound. C) By comparing physical constants with listed values. D) By visualizing the particles in the solid state.
What do molecular models represent? A) The ratio of atoms in a compound. B) The chemical symbols of elements. C) The fixed volume and shape of solids. D) The 3-dimensional shape of molecules.
Answers to Prerequisite Quiz:
C. The simplest ratio of atoms in the compound.
A. NaCl
A. They are closely packed and vibrate in fixed positions.
B. To visualize the 3-dimensional shape of molecules.
A. A bond between two atoms.
Answers to End of Lesson Quiz:
A. Number and kind of atoms in each molecule.
C. To visualize the 3-dimensional shape of molecules.
B. Ionic compounds.
A. By counting the number of atoms in each element.
D. The 3-dimensional shape of molecules.
Fantastic work! 🎉 You have successfully completed Lesson 12. You're doing an excellent job of understanding atomic symbols, chemical formulas, and molecular models. If you have any further questions, feel free to ask. Keep up the great work! 😊