Materials and energy



Materials and energy

Integrated Science Questions

  1. What is the basic structure of an atom?
Answer: Protons, neutrons, and electrons.
  1. What are atoms represented by?
Answer: Symbols.
  1. What is formed when atoms share or exchange electrons?
Answer: Molecules.

Physical Change

  1. What is a physical change?
Answer: A change in state without changing the chemical composition.
  1. How do atoms arrange themselves in solids?
Answer: In a fixed, orderly arrangement.
  1. At what temperatures does water change state?
Answer: 0°C (solid to liquid), 100°C (liquid to gas).

Mixtures

  1. What is a mixture?
Answer: A physical blend of two or more substances.
  1. How can mixtures be separated?
Answer: Through methods like filtration, decantation, and evaporation.

Mass and Weight

  1. What is the difference between mass and weight?
Answer: Mass is a measure of the amount of matter, while weight is the force exerted on that matter by gravity.
  1. How is weight calculated?
Answer: By multiplying mass by the acceleration due to gravity.

Density

  1. What is density?
Answer: The ratio of mass to volume of a substance.
  1. How is density determined?
Answer: By measuring the mass and volume of a substance.

Heat Transfer

  1. What are the types of heat transfer?
Answer: Conduction, convection, and radiation.
  1. How does a vacuum flask work?
Answer: By reducing heat transfer through conduction and convection.

Reflection and Refraction of Light

  1. What is reflection?
Answer: The change in direction of light when it hits a surface.
  1. What is refraction?
Answer: The bending of light as it passes from one medium to another.

Composition of Air

  1. What are the main components of air?
Answer: Nitrogen, oxygen, carbon dioxide, and other gases.
  1. What is the proportion of each substance in air?
Answer: Approximately 78% nitrogen, 21% oxygen, 0.04% carbon dioxide.

The Composition of Matter

  1. What is the difference between an element and a compound?
Answer: An element is made of one type of atom, while a compound is made of two or more types of atoms.
  1. Give an example of a diatomic molecule.
Answer: Oxygen (O2).
  1. What is the purpose of an electron microscope?
Answer: To create images of atoms.
  1. What is the composition of most of an atom?
Answer: Empty space.
  1. What are the three basic subatomic particles that make up an atom?
Answer: Protons, neutrons, and electrons.
  1. What is the smallest unit of matter?
Answer: An atom.
  1. What is a substance made of two or more atoms of different elements called?
Answer: A chemical compound.
  1. Give an example of a chemical compound.
Answer: Water (H2O).

The Basic Structure of an Atom

  1. What is the centre of an atom called?
Answer: The nucleus.
  1. What is the nucleus composed of?
Answer: Protons and neutrons.
  1. What percentage of an atom's mass is made up by the nucleus?
Answer: 99.996%.
  1. What are the two different kinds of subatomic particles held together by atomic forces in the nucleus?
Answer: Protons and neutrons.
  1. What is the atomic number of an element?
Answer: The special number of protons in its nucleus.
  1. What is the difference in electric charge between protons and neutrons?
Answer: Protons are positively charged, while neutrons are neutral.
  1. Where do electrons move in an atom?
Answer: In shells (energy levels) around the nucleus.
  1. How many electrons can the first shell or energy level hold?
Answer: Two electrons.
  1. How many electrons can the second shell or energy level hold?
Answer: Eight electrons.
  1. How many electrons can the third shell or energy level hold?
Answer: Eighteen electrons.

The Basic Structure of an Atom

  1. Why is an atom neutral?
Answer: Because it has equal numbers of protons and electrons.
  1. What is the size of the nucleus compared to the whole atom?
Answer: The nucleus is very small compared to the whole atom.
  1. What is the purpose of making a model of an atom?
Answer: To visualize and understand the structure of an atom.
  1. What materials are used to make a model of an atom?
Answer: Paper plate, glue, compass, dried lentils, dried peas, and marker pen.
  1. What do the dried beans represent in the model of an atom?
Answer: Protons and neutrons.
  1. What do the dried lentils represent in the model of an atom?
Answer: Electrons.
  1. What information should be researched about an element for the enrichment activity?
Answer: Date of discovery, person who discovered it, type of element, appearance, and uses.
  1. What does the term "concentric" mean?
Answer: Circles with the same centre.

Elements and Their Symbols

  1. What is a chemical element?
Answer: A pure chemical substance that consists of one type of atom.
  1. What is a chemical symbol?
Answer: A short way of representing an element.
  1. How are elements divided?
Answer: Into metals, metalloids, and non-metals.
  1. What is the symbol for aluminium?
Answer: Al.
  1. What is the symbol for oxygen?
Answer: O.

The Formation of Simple Molecules

  1. What is a molecule?
Answer: An electrically neutral group of two or more atoms held together by chemical bonds.
  1. What can a molecule consist of?
Answer: Atoms of the same chemical element or more than one type of chemical element.
  1. What is a chemical bond?
Answer: The pull that joins two atoms.

Test Yourself on Atoms

  1. Why do atoms have no charge?
Answer: Because they have equal numbers of protons and electrons.
  1. Which subatomic particle gives an element its identity?
Answer: The proton.
  1. Which subatomic particle has no electric charge?
Answer: The neutron.
  1. What role does the neutron play in the atom?
Answer: It helps to determine the mass of the atom.


Molecular Formulas

  1. What does the molecular formula H2O indicate?
Answer: That water is made from two atoms of hydrogen and one atom of oxygen.
  1. What does the number 2 in H2O represent?
Answer: The number of atoms of hydrogen.
  1. What does the absence of a number to the right of the O in H2O indicate?
Answer: That there is only one atom of oxygen.

Molecular Representations

  1. What do the two identical spheres joined together in Figure 6A represent?
Answer: An oxygen molecule.
  1. What do the four blue balls at (a) in Figure 6 represent?
Answer: The four shared electrons that join the two oxygen atoms.
  1. What do the two identical spheres joined together in Figure 7A represent?
Answer: A hydrogen molecule.
  1. What do the two blue balls at (a) in Figure 7 represent?
Answer: The two shared electrons that join the two hydrogen atoms.

Molecular Representations

  1. What do the two identical spheres joined together in Figure 8A represent?
Answer: A nitrogen molecule.
  1. What do the six blue balls at (a) in Figure 8 represent?
Answer: The six shared electrons that join the two nitrogen atoms.
  1. What do the red spheres in Figure 9A represent?
Answer: Oxygen atoms.
  1. What does the black sphere in Figure 9A represent?
Answer: A carbon atom.
  1. What do the four blue balls at (a) and (b) in Figure 9 represent?
Answer: The two groups of four shared electrons that join the two oxygen atoms to the carbon atom.


Molecular Formulas

  1. What does the molecular formula H2O show?
Answer: The number, ratio, and type of atoms that make up a molecule of water.
  1. What does the number 2 in 2H2O represent?
Answer: The number of molecules of water.
  1. How many hydrogen atoms and oxygen atoms are there in 2H2O?
Answer: Four hydrogen atoms and two oxygen atoms.
  1. What is the definition of a molecular formula?
Answer: A short way of writing the name of a molecule, showing the number, ratio, and type of atoms.

Molecular Representations

  1. What do the two identical white spheres in Figure 10A represent?
Answer: Hydrogen atoms.
  1. What does the red sphere in Figure 10A represent?
Answer: An oxygen atom.
  1. What do the blue balls at (a) and (b) in Figure 10 represent?
Answer: The two shared electrons that join the two hydrogen atoms to the oxygen atom.

  1. Is C an element or a compound?
Answer: An element.
  1. What elements are HCl made of?
Answer: Hydrogen and chlorine.
  1. Is O2 an element or a compound?
Answer: An element.
  1. What elements are NaCl made of?
Answer: Sodium and chlorine.
  1. Is Fe an element or a compound?
Answer: An element.
  1. What elements are H2O made of?
Answer: Hydrogen and oxygen.
  1. What elements are CH4 made of?
Answer: Carbon and hydrogen.
  1. What elements are CO2 made of?
Answer: Carbon and oxygen.
  1. What elements are N2 made of?
Answer: Nitrogen.

Symbols and Chemical Formulas

  1. What is the symbol for sodium?
Answer: Na.
  1. What is the chemical formula for carbon monoxide?
Answer: CO.
  1. What is the symbol for hydrogen?
Answer: H.
  1. What is the symbol for aluminium?
Answer: Al.
  1. What is the chemical formula for carbon dioxide?
Answer: CO2.
  1. What is the chemical formula for water?
Answer: H2O.

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