Properties of matter

my generic notes:

Objective 8 - Properties of matter:

• Element - The simplest kind of substance that cannot be broken down into anything simpler. All its atoms have the same number of protons, and it is only made of one type of atom.
• Compound - a substance with 2 or more elements (different) chemically bonded together

⚛️ Sodium chloride is a lot of sodium ions attracted to chloride ions, which are attracted to sodium ions. This forms NaCl as a lattice (Note: lattice only refers to ionic compounds), as these ions occur in an equal ratio.

• Molecules: Elements bonded covalently. A particle containing two or more atoms joined together by covalent bonds. - has to involve non-metals.
  • Atom: Smallest particle of an element that can exist on its own. It is made up of subatomic particles that are indivisible.
• Ion: An atom or groups of atoms that has become positively or negatively charged by losing or gaining electrons.
  • Positively charged - cation (+ve) - formed by losing electrons
  • Negatively charged - anion (-ve) - formed by gaining electrons

Anions are attracted to cathodes - Michael Faraday

Mass of conservation: no matter can be created nor destroyed

Chemical symbol

• Letter of pair of letters used to represent an element
• Examples, S, Fe

Chemical formulae:

• The molecular formula gives the total number of atoms of each element present in one molecule.
• The empirical formula gives the simples whole number ratio of atoms of each element present in a compound
• Examples - $Na^+Cl^-$ , $CH_2O$
• Chemical formula includes both molecular and empirical.

Stoichiometry is a ratio of substances in an equation when they react.

• When you balance a formula, you put stoichiometric coefficients.
• It is used in calculations.
• The relationship between the relative quantities of substances taking part in a chemical reaction.

Chemical equation:

• Shows the reactants taking part in a chemical reaction and the products from the reactants in the correct proportions.
• Reactants are on the left, and products are on the right.

Pure substances:

• Have a fixed or constant composition
• Cannot be separated by physical means
• Have well defined physical properties, e.g.:
  • melting point
  • boiling point
  • hardness
  • density
  • colour
  • solubility
  • conductivity
• Have constant chemical properties.
• Elements, molecules and compounds are pure substances

Mixtures:

• contains two or more different substances, in proportions that can vary
• properties vary with composition, depends on the identity and amounts of constituents/substances
• properties of individual constituents/substances can be used to separate the mixture

Homogenous materials:

• have uniform composition throughout
• includes all pure substances (elements and compounds) and some mixtures
• the only kind of mixture that is homogenous is a solution e.g. salt water

Heterogenous materials:

• heterogenous materials are non-uniform - you can see differences from one section to another
• the constituents are physically separated, e.g. in a different phase
• Examples include:
  • Granite (mixtures of different mineral grains)
  • Milk (fat globules suspended in water)
  • Toothpaste (solid particles suspended in liquid)

Solution:

• Where a minor component (the solute) is uniformly distributed within a major component which is usually a liquid (the solvent)

3 States of matter:

• Solid - molecules are closely bonded together, usually in firm chemical structures. Low kinetic energy - has fixed volume
• Liquid - molecules are loosely bonded together, there are some small chemical bonds, flows freely and is not found in firm states. Medium kinetic energy - has fixed volume
• Gas - weak attraction in molecules, high kinetic energy. Gasses attempt to fill the space of their containment.

Processes of change:

• Gas to liquid - condensation
• Liquid to gas - evaporation
• Solid to liquid - melting
• Liquid to solid - freezing/solidification
• Solid to gas - sublimation
• Gas to solid - deposition

Classification of matter:

Note - mixtures can be separated into pure substances using differences in physical properties.

Pure substances:

Note - compounds are separated by chemical means

• Compounds
• Elements

Mixtures:

• Homogenous mixtures - you can shine light through a mixture, if it passes through and light does not change, it is homogenous
• Heterogenous mixtures - if light scatters, it is heterogenous

Solutions (aq) are mixtures!!! :) thank you ethan widjaja

notes from ms pilling herself

1.b Mixtures:

NOTE: All mixtures are physically mixed together, so they can be separated using physical properties.

Definition of a few key things:

• Atom - the smallest particle of an element that can exist. It is made up of subatomic particles which are not indivisible (in chemistry)

• Molecule - (A particle with ) two or more atoms covalently bonded together.

• Element - The simplest kind of substance that cannot be broken down into anything else, comprised of atoms with the same number of protons.

• Compound - two or more elements (THEY HAVE TO BE DIFFERENT!) chemically bonded together.

• Mixture - two or more substances that are not chemically bonded together, in varying proportions

  • Properties vary with composition, depends on the identity/amounts of constituents
  • Properties of individual constituents can be used to separate these constituents from a mixture.
  • KEYWORD: Constituents

• Pure - only present in a fixed composition

  • Elements, compounds, molecules fit this description - some mixtures are pure, e.g. solutions

  • Cannot be separated using physical means

  • Physical properties are well-defined:

    

  • Chemical properties are consistent

• Impure - contains a non-uniform mixture of substances that are not chemically bonded together.

• Homogenous - uniform composition

  • called it

• Heterogenous - non-uniform composition

  • Constituents of heterogenous substances can be separated using physical means

  • Heterogenous substances are mixtures!!!

Related Class Notes:

• R-AECHE-1
• R-AECHE-2
• R-AECHE-3
• R-AECHE-4
• R-AECHE-5
• R-AECHE-7
• R-AECHE-18
• R-AECHE-23

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