chemistry paper 1

Cards (1068)

  • An atom is the smallest part of an element that can exist
  • An element is a substance of only one type of atom
  • Elements are listed in the periodic table; there are approximately 100
  • Elements can be classified into two groups based on their properties: metals and non-metals
  • Elements may combine through chemical reactions to form new products called compounds
  • A compound is two or more elements combined chemically in fixed proportions which can be represented by formulae
  • Compounds do not have the same properties as their constituent elements
  • A mixture consists of two or more elements or compounds not chemically combined together; it does have the same chemical properties
  • Methods to separate mixtures without involving chemical reactions are:
    • Filtration
    • Crystallisation
    • Simple distillation
    • Fractional distillation
    • Chromatography
  • Simple distillation separates liquid from a solution by boiling off the liquid, condensing it, and reading the boiling point of the pure liquid
  • Crystallisation/evaporation separates a solid dissolved in a solvent by heating the solution until the solvent evaporates, leaving the solid behind
  • Fractional distillation separates a mixture of liquids based on their different boiling points using a fractionating column
  • Filtration separates an insoluble solid suspended in a liquid by catching the solid in the filter paper
  • Chromatography separates a mixture of substances dissolved in a solvent by allowing the solvent to rise on a piece of paper, separating the mixture into components
  • A separating funnel is used to separate immiscible liquids based on their different densities
  • The plum-pudding model describes the atom as a ball of positive charge with negative electrons embedded in it
  • The Bohr/nuclear model suggests electrons orbit the nucleus at specific distances and came about from alpha scattering experiments
  • Protons are smaller, positive particles discovered in the nucleus through later experiments
  • James Chadwick's work provided evidence for the existence of neutrons in the nucleus
  • The structure of an atom includes a small central nucleus made up of protons and neutrons, surrounded by electrons
  • Relative masses and charges of proton, neutron, and electron:
    • Masses: 1, 1, very small
    • Charges: 1, 0, -1 (respectively)
  • Atoms are electrically neutral because they have an equal number of protons and electrons
  • Atoms are electrically neutral because they have the same number of electrons and protons
  • The radius of an atom is 0.1 nm
  • The radius of a nucleus is 1 x 10^-14 m, which is 1/10000 the size of the atom
  • The number of protons in the nucleus is called the atomic number
  • Atoms of the same element have the same number of protons in the nucleus, which is protons
  • The majority of the mass of an atom is in the nucleus
  • The mass number is the total number of protons and neutrons
  • To calculate the number of neutrons, subtract the atomic number from the mass number
  • An isotope is atoms of the same element with a different number of neutrons; isotopes of the same element have the same chemical properties as they have the same electronic structure
  • The relative atomic mass is the average mass value that considers the mass and abundance of isotopes of an element, based on a scale where the mass of 12C is 12
  • Electronic configurations of He (2), Be (4), F (9), Na (11), and Ca (20) are:
    • He: 2
    • Be: 2,2
    • F: 2,7
    • Na: 2,8,1
    • Ca: 2,8,8,2
    These configurations demonstrate how shells are occupied by electrons
  • Ions are charged particles formed when atoms lose electrons (positive ions) or gain electrons (negative ions)
  • Properties of metals and non-metals:
    • Metals have high boiling/melting points, conduct heat and electricity, are shiny, malleable, have high density, and form basic oxides
    • Non-metals have low boiling/melting points, don't conduct heat or electricity (except graphite), are dull, brittle, have low density, and form acidic oxides
  • When a metal reacts with a non-metal, an ionic compound (made of positive and negative ions) is formed
  • When a non-metal reacts with a non-metal, a molecular compound containing covalently bonded atoms is formed, where atoms share electrons
  • Solute is a substance dissolved in a solvent to form a solution. Miscible substances mix, while immiscible substances don't. Soluble substances dissolve, while insoluble substances don't
  • The columns of the periodic table are called groups
  • The rows of the periodic table are called periods