Structure of Matter

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Questions and Answers

What determines the element of an atom?

The number of neutrons

The number of protons (correct)

The mass of the atom

The number of electrons

Which of the following describes ionic bonds?

Atoms share electrons

Atoms attract due to magnetic forces

Atoms transfer electrons (correct)

Atoms have no interaction

What state of matter is characterized by atoms that are far apart and move randomly?

Gas (correct)

Plasma

Liquid

Solid

Which of these is a characteristic of pure substances?

They have a uniform and definite composition Signup and view all the answers

What is the smallest unit of a compound that retains its properties?

Molecule Signup and view all the answers

What type of particles are protons?

Positively charged Signup and view all the answers

Which statement about electrons is true?

They orbit the nucleus in shells. Signup and view all the answers

How are mixtures classified compared to pure substances?

Mixtures contain multiple substances physically combined. Signup and view all the answers

What characterizes ionic bonds?

Atoms transfer electrons, resulting in charged ions. Signup and view all the answers

What is true about solid matter?

Atoms are closely packed and only vibrate in fixed positions. Signup and view all the answers

Which of the following correctly describes pure substances?

Contain only one type of atom or molecule. Signup and view all the answers

What is the main function of protons within an atom?

Determine the element's identity. Signup and view all the answers

What does the atomic number of an atom represent?

The number of protons in the nucleus. Signup and view all the answers

How are electron shells structured in an atom?

Electrons occupy defined energy levels orbiting the nucleus. Signup and view all the answers

What happens to the number of neutrons in different isotopes of the same element?

They can vary, resulting in different mass numbers. Signup and view all the answers

Which characteristic is true of gases compared to liquids and solids?

Gases have particles that move randomly and are far apart. Signup and view all the answers

What is the trend observed in the oxides of Period 3 elements?

Basicity decreases and acidity increases from sodium to chlorine. Signup and view all the answers

Which oxide is classified as amphoteric in Period 3?

Aluminum oxide Signup and view all the answers

How is the valency of an atom determined?

By the number of electrons in the outermost shell. Signup and view all the answers

What does valency indicate regarding an atom?

The number of hydrogen atoms that can combine with it. Signup and view all the answers

Which of the following is an example of a divalent atom?

Oxygen Signup and view all the answers

In terms of reactivity, how does valency affect an element?

Higher valency means stronger bonds are formed. Signup and view all the answers

Which valency type describes an atom that can form three bonds?

Trivalent Signup and view all the answers

Why is understanding valency crucial in chemistry?

It helps predict how different elements interact in chemical reactions. Signup and view all the answers

What is the role of valency in chemistry?

It helps predict chemical reactions and properties of substances. Signup and view all the answers

Which of the following statements accurately describes polyatomic ions?

They behave as a single unit during chemical reactions. Signup and view all the answers

Which of the following is a common polyatomic ion?

Hydroxide (OH⁻) Signup and view all the answers

How is the charge on a polyatomic ion determined?

By the total number of protons and electrons in the group of atoms. Signup and view all the answers

What distinguishes polyatomic ions from free radicals?

Free radicals have unpaired electrons and are highly reactive. Signup and view all the answers

Which of the following represents a polyatomic ion with a negative charge?

Sulfate (SO₄²⁻) Signup and view all the answers

Which statement is true about the behavior of atoms in polyatomic ions?

The atoms are covalently bonded and function as a single unit. Signup and view all the answers

Which of the following describes the composition of polyatomic ions?

They consist of two or more atoms that are tightly bonded. Signup and view all the answers

Which property is characteristic of metals?

Good conductors and malleable Signup and view all the answers

What is an example of a non-metal?

Carbon Signup and view all the answers

Which of the following is a property of metalloids?

Intermediate properties and semiconductors Signup and view all the answers

At what temperature does silicon melt?

1,410°C Signup and view all the answers

Which industry heavily utilizes silicon due to its semiconducting properties?

Electronics Signup and view all the answers

What is a characteristic property of boron?

Relatively low reactivity at high temperatures Signup and view all the answers

Which of the following is NOT a use of silicon?

Insulation materials Signup and view all the answers

How does amorphous boron typically react under high temperatures?

React with oxygen and sulfur Signup and view all the answers

Study Notes

Matter is composed of tiny particles called atoms, the fundamental building blocks of substances.
Atoms contain three main subatomic particles: protons (positively charged), neutrons (neutral), and electrons (negatively charged).
The identity of an atom is determined by the number of protons; for example, an atom with 6 protons is carbon, while 8 protons indicate oxygen.

Molecules and Bonds

Atoms combine to form molecules, the smallest units of compounds retaining properties of those compounds.
Covalent bonds occur when atoms share electrons, while ionic bonds occur when electrons are transferred, creating charged ions.

States of Matter

The three fundamental states are:
- Solid: Atoms are closely packed and vibrate in fixed positions.
- Liquid: Atoms are close together but move around each other, maintaining a definite volume while taking the shape of their container.
- Gas: Atoms are far apart and move randomly, having neither a definite shape nor volume.

Classifications of Matter

Pure Substances: Uniform composition consisting of one type of atom or molecule (e.g., elements like gold and compounds like water).
Mixtures: Consist of two or more substances physically combined (e.g., air and salad).

Atomic Structure

The nucleus is the dense core containing protons (which determine the element) and neutrons (that contribute to atomic mass).
Electron shells contain electrons that orbit the nucleus; their quantity equals the number of protons in a neutral atom.

Atomic Number and Mass

Atomic number refers to the number of protons, while mass number is the sum of protons and neutrons.
Elements can have the same atomic number but different mass numbers due to varying neutrons.

Classification Relationships

Metals: Shiny, good conductors, malleable (e.g., Iron, Copper).
Non-Metals: Dull, poor conductors, brittle (e.g., Oxygen, Carbon).
Metalloids: Have intermediate properties; act as semiconductors (e.g., Silicon).

Properties of Silicon

Second most abundant element in the Earth's crust, found in crystalline and amorphous forms.
Melting point is 1,410°C; used primarily in electronics (transistors and diodes), solar cells, and computer equipment.

Properties of Boron

Black, crystalline solid with a high melting point of 2,200°C and relatively low reactivity.
Reacts only at very high temperatures with some substances, forming various compounds.

Chemical Formulae

A chemical formula represents the composition of a compound using element symbols and numerical subscripts.
Valency reflects an atom's bonding capacity, based on the number of electrons in the outer shell.

Types of Valency

Monovalent: One bond (e.g., Hydrogen).
Divalent: Two bonds (e.g., Oxygen).
Trivalent: Three bonds (e.g., Nitrogen).
Quadrivalent: Four bonds (e.g., Carbon).

Polyatomic Ions

Groups of atoms bonded together that carry an overall charge; behave as a single unit in reactions.
Examples include Nitrate (NO₃⁻), Sulfate (SO₄²⁻), Phosphate (PO₄³⁻), and Ammonium (NH₄⁺).

Summary of Trends in Periodic Elements

The oxides of Period 3 elements show a trend from basicity to acidity, transitioning from sodium to chlorine, with aluminum oxide acting as amphoteric.

Importance of Understanding Structure of Matter

Knowledge of atomic and molecular structures is fundamental in explaining material properties, behavior in reactions, and applications in chemistry, materials science, and physics.

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Description

Explore the intricate structure of matter in this quiz based on Science Lesson 3 for Grade 10. Understand the composition of matter, focusing on atoms and their subatomic particles. Test your knowledge and learn about the essential building blocks of all substances.

Structure of Matter - Science Lesson 3 G10