Symbol: Hg
State: Liquid
Hydrogen (H)
Symbol: H
State: Gas
Helium (He)
Symbol: He
State: Gas
Classify the following as metals, non-metals and metalloids.
Sodium, Bismuth, Silver, Nitrogen, Silicon, Carbon, Chlorine, Iron, Copper
Metals:
- Sodium (Na)
- Bismuth (Bi)
- Silver (Ag)
- Iron (Fe)
- Copper (Cu)
Non-metals:
- Nitrogen (N)
- Carbon (C)
- Chlorine (Cl)
Metalloids:
- Silicon (Si)
Classify the following as elements and compounds.
Water, Common salt, Sugar, Carbon dioxide, Iodine and Lithium
Elements:
- Iodine
- Iodine (I) is an element.
- Lithium
- Lithium (Li) is an element.
Compounds:
- Water
- Water (H₂O) is a compound.
- Common salt
- Common salt (NaCl) is a compound.
- Sugar
- Sugar (C₆H₁₂O₆) is a compound.
Carbon dioxide
- Carbon dioxide (CO₂) is a compound.
Write the chemical formula for the following elements.
- Hydrogen: H₂
- Nitrogen: N₂
- Ozone: O₃
- Sulfur (Sulphur): S
What are elements? What are they made of? Give two examples.
Elements are substances that consist of only one type of atom. They are the simplest form of matter and cannot be broken down into simpler substances by chemical means. Each element is characterized by its unique atomic number, which represents the number of protons in the nucleus of its atoms.
Elements are made up of atoms, which are the smallest units of an element that retain its chemical properties. Atoms consist of a nucleus containing protons and neutrons, surrounded by a cloud of electrons orbiting the nucleus.
Two examples of elements are:
Oxygen (O): Oxygen is an element that exists as diatomic molecules (O₂) in its natural state. It is essential for respiration and combustion, among other biological and chemical processes.
Iron (Fe): Iron is a metal element commonly found in the Earth’s crust. It is known for its strength and durability, and it is used in various industrial applications, including construction and manufacturing.
Define molecule.
A molecule is a group of two or more atoms that are chemically bonded together. These atoms can be of the same element (as in diatomic molecules like oxygen, O2) or different elements (as in compound molecules like water, H2O). Molecules are the smallest units of a compound that retain the chemical properties of that compound. They can exist as discrete units or as part of larger structures. Molecules can vary in size and complexity, from simple diatomic molecules to large, complex molecules like proteins or DNA.
What are compounds? Give two examples.
Compounds are substances composed of two or more different elements that are chemically bonded together in fixed proportions. These elements combine through chemical reactions to form compounds with properties different from those of the individual elements.
Two examples of compounds are:
Water (H2O): Water is a compound composed of two hydrogen atoms bonded to one oxygen atom. It is essential for life and is commonly found in liquid form on Earth.
Carbon dioxide (CO2): Carbon dioxide is a compound composed of one carbon atom bonded to two oxygen atoms. It is a gas that is produced during combustion and respiration and plays a crucial role in the Earth’s carbon cycle.
Give an example for the elements derived from their Latin names.
One example of an element derived from its Latin name is:
Ferrum (Fe): The element with the symbol Fe is derived from its Latin name “ferrum.” In English, it is known as iron.
What is atomicity of elements?
The atomicity of an element refers to the number of atoms that are chemically bonded together to form a single molecule of that element in its natural state.
For example:
Oxygen (O2) has an atomicity of 2 because two oxygen atoms are chemically bonded together to form a single molecule of oxygen gas.
Phosphorus (P4) has an atomicity of 4 because four phosphorus atoms are chemically bonded together to form a single molecule of white phosphorus.
Calculate the atomicity of H2SO4
To calculate the atomicity of H2SO4H2SO4, which is sulfuric acid, we need to count the total number of atoms in one molecule of sulfuric acid.
The chemical formula for sulfuric acid (H2SO4H2SO4) indicates that there are:
2 hydrogen atoms (H)
1 sulfur atom (S)
4 oxygen atoms (O)
So, the total number of atoms in one molecule of sulfuric acid is 2+1+4=72+1+4=7.
Therefore, the atomicity of H2SO4H2SO4 is 7.
Answer in detail.
Differentiate metals and non-metals.
Metals:
- Metals are typically solid at room temperature (except mercury).
- They are lustrous (shiny) in appearance.
- Metals are good conductors of heat and electricity.
- They are malleable (can be hammered into thin sheets) and ductile (can be drawn into wires).
- Metals tend to lose electrons to form positively charged ions (cations) in chemical reactions.
- Examples of metals include iron, copper, aluminum, and gold.
Non-metals:
- Non-metals can exist in various states at room temperature: solid (like sulfur), liquid (like bromine), or gas (like oxygen).
- They are typically dull or have a matte appearance.
- Non-metals are poor conductors of heat and electricity.
- They are brittle (break easily) and are not malleable or ductile.
- Non-metals tend to gain electrons to form negatively charged ions (anions) in chemical reactions.
- Examples of non-metals include oxygen, sulfur, carbon, and nitrogen.
Explain the characteristics of compounds
Characteristics of Compounds:
- Compounds are pure substances composed of two or more different elements chemically bonded together.
- The ratio of elements in a compound is fixed, giving compounds specific chemical properties distinct from their constituent elements.
- Compounds can be represented by chemical formulas, indicating the types and numbers of atoms in a single molecule of the compound.
- Compounds have specific physical and chemical properties different from those of the elements they are composed of.
- Compounds can be decomposed into simpler substances (elements or other compounds) through chemical reactions, but the elements cannot be separated by physical means.
Differentiate between elements and compounds.
Elements:
- Elements are pure substances composed of only one type of atom.
- They cannot be broken down into simpler substances by chemical means.
- Each element has a unique set of properties determined by the number of protons in its nucleus.
- Examples: Oxygen (O), Iron (Fe), Hydrogen (H).
Compounds:
- Compounds are pure substances composed of two or more different elements chemically bonded together.
- They have fixed ratios of elements and distinct chemical properties.
- Compounds can be broken down into simpler substances (elements or other compounds) by chemical reactions.
- Examples: Water (H2O), Carbon dioxide (CO2), Sodium chloride (NaCl).
Write any five characteristics of compounds.
- Compounds are composed of two or more different elements chemically bonded together.
- The ratio of elements in a compound is fixed, giving compounds specific chemical properties.
- Compounds have distinct physical and chemical properties different from their constituent elements.
- Compounds can be represented by chemical formulas, indicating the types and numbers of atoms in a single molecule.
- Compounds can be decomposed into simpler substances through chemical reactions, but the elements cannot be separated by physical means.
Compare the properties of metals and non- metals. Give three examples for each.
Properties of Metals:
- Metals are typically solid at room temperature (e.g., iron, copper, aluminum).
- They are good conductors of heat and electricity (e.g., copper wires).
- Metals are malleable and ductile, allowing them to be hammered into thin sheets and drawn into wires (e.g., gold leaf, aluminum wires).
Properties of Non-metals:
- Non-metals can exist in various states at room temperature (e.g., oxygen gas, sulfur solid, bromine liquid).
- They are poor conductors of heat and electricity (e.g., rubber, sulfur).
- Non-metals are brittle and not malleable or ductile (e.g., sulfur, carbon in the form of graphite).
Write down the properties of metalloids.
Properties of Metalloids:
- Metalloids have properties intermediate between metals and non-metals.
- They can exhibit characteristics of both metals and non-metals depending on the conditions.
- Metalloids are typically semiconductors, meaning they have electrical conductivity between that of metals and non-metals.
- Examples of metalloids include silicon (Si), germanium (Ge), and arsenic (As).
VII. Rewrite the given sentence in correct form.
Elements contain two or more kind of atoms and compounds contain only one kind of atom.
Elements contain only one kind of atom, while compounds contain two or more different kinds of atoms.
