Topic 1: Materials and Their Atoms

Chemistry is the study of matter. Matter is anything that has mass and takes up space. Matter consists of particles include atoms, ions, subatomic particles and molecules. Materials are anything made for matter. Materials are described in terms of physical and chemical properties. Chemical Properties are determined by transforming the material into another chemical substance. Physical Properties are observed and measured without transforming the material into another substance.EXAMPLEFlammability is a chemical property. Flammable ignite when energy and oxygen are supplied. Carbon Dioxide (CO2), water vapour (H2O) and other new materials are pro

From the SACE Chemistry Guide (2017)The uses of materials are related to their properties, including solubility, thermal and electrical conductivities, melting point, and boiling point.Nanomaterials are substances that contain particles in the size range 1–100 nm.Suggest uses of materials, including nanomaterials, given their properties and vice versa. All materials consist of atoms.Atoms are commonly modelled as consisting of electrons orbiting a nucleus containing protons and neutrons.Emission and absorption spectra of elements provide evidence that electrons are arranged in distinct energy levels and can be used to identify some elements in matter.Atomic number and mass number provide information about the numbers of subatomic particles in an atom.Many elements consist of a number of different isotopes, which have different physical properties but the same chemical properties.Represent isotopes of an element using appropriate notation.The arrangement of electrons in atoms and monatomic ions can be described in terms of shells and subshells.Write the electron configuration using subshell notation of an atom of any of the first 38 elements in the periodic table.The quantities of different substances can be conveniently compared using the mole unit.The relative atomic mass of an element is determined from all the isotopes of that element.The number of moles of atoms in a sample can be determined from the number of atoms present or from the mass of the atoms.· Undertake calculations using the relationshipand its rearrangements.In the modern periodic table, elements are arranged in order of increasing atomic number, and display periodic trends in their properties.Identify trends in atomic radii, valencies, and electronegativities, across periods and down groups of the periodic table.The position of an element in the periodic table is related to its metallic or non-metallic character.· Identify the position of an atom in the periodic table given its electron configuration.Identify the s, p, d, and f blocks of the periodic table.Materials can be classified according to their structure and bonding into four types of substances.Melting points can be used to classify materials into molecular and non-molecular lattices. Electrical conductivity of non-molecular materials provides evidence for three types of primary bonding: metallic, ionic, and covalent.Classify materials as molecular, metallic, ionic, and covalent network, given relevant conductivity and melting point data.The formation of bonds between atoms results in stable valence-shell configurations.Energy is released when bonds are formed. Energy is required to break bonds.Metallic, ionic, and covalent bonds are the strong forces of attraction (primary bonds) between particles.Metallic BondingMetallic bonding is the force of attraction between metal cations and their delocalised valence electrons.The physical properties of metallic elements can be explained using the model for metallic bonding.· Explain the melting and boiling points, and electrical conductivities of metallic elements.Ionic BondingValence electrons are transferred from a metallic atom to a non-metallic atom to form ions. Ionic bonding is the force of attraction between the oppositely charged ions.· Predict the charge on the monatomic ion formed by an element, using its position in the periodic table.· Write the electron configuration, using subshell notation of the monatomic ion of any of the first 38 elements of the periodic table.Ionic compounds are continuous and are represented by empirical formulae.· Write formulae for ionic compounds given the charges on the ions.The properties of ionic compounds can be explained using the model for ionic bonding.Explain the melting and boiling points, and electrical conductivities of ionic compounds.Covalent BondingNon-metallic atoms share electrons to form covalent bonds.· Use electron-dot diagrams and structural formulae to show covalent bonds between non-metallic atoms.A covalent bond may be polar or non-polar.· Use electronegativity values, or the position of atoms in the periodic table, to predict and explain the polarity of a covalent bond.· Indicate the polarity of a covalent bond, using the appropriate convention. Covalent bonding is found in molecular and non-molecular (continuous) substances.A molecule can be represented by a molecular formula.A continuous covalent substance is represented by an empirical formula.The physical properties of continuous covalent substances can be explained using the model for covalent bonding.Explain the melting point, hardness, and electrical conductivity of continuous covalent substances. The percentage composition of elements in compounds can be determined from the molar masses of the atoms.· Undertake calculations of percentage composition, by mass, of elements in compounds.The number of moles of particles (molecules, ions) in a sample can be determined from the mass of the sample and the molar masses of the particles.· Undertake calculations using the relationshipand its rearrangements for molecules, and for ions and their compounds. The shapes of molecules can be explained and predicted using three-dimensional representations of electrons as charge clouds, and using valence-shell electron‑pair repulsion (VSEPR) theory.Draw and annotate diagrams showing covalent bonds, non-bonding pairs, and shapes of molecules and ions in which there is only one central atom and up to eight valence electrons. The polarity of a molecule results from the polar character of the bonds and their spatial arrangement.Predict and explain whether or not a molecule is polar, given its spatial arrangement The physical properties of molecular substances can be explained by considering the nature and strength of the forces of attraction between the molecules.Secondary interactions between molecules are much weaker than primary metallic, ionic, and covalent bonds.The shape, polarity, and size of molecules can be used to explain and predict the nature and strength of secondary interactions.Dispersion forces exist between all molecules. Their strength depends on the size and shape of the molecules.Dipole–dipole interactions exist between polar molecules and their strength depends on the polarity and size of the molecules.· Predict the relative strengths of interactions between molecules, given relevant information.Hydrogen bonding is a particularly strong form of dipole–dipole interaction that exists between molecules.· Draw diagrams showing partial charges and hydrogen bonding between HF, H2O, and NH3 molecules.· Explain the boiling points of HF, H2O, and NH3 in terms of hydrogen bonding between the molecules.