Module 1 Flashcards
- Define the terms matter, pure substances and mixtures
Define Matter
Matter is anything that has mass and occupies space.
What can matter be classified as?
It can be classified as pure
substance (element or compound) or mixture (homogenous or heterogenous).
What is a pure substance
sample of matter with both definite, constant composition and distinct
chemical properties.
What is a mixture?
are two or more pure substances physically combined together. It has variable composition and variable physical properties.
Physical properties of
mixtures can be changed, unlike compounds.
- Identify the differences between elements and compounds
Elements
are composed of one type of atom.
Most non-metallic elements form discrete molecules with definite number of atoms.
Sulfur
forms a discrete molecule of 8 atoms.
Some non-metallic elements are monatomic (noble gases). Noble gases are generally
chemically inert.
Some non-metallic atoms form covalent networks or giant molecules.
Carbon forms
covalent networks of diamond and graphite, and giant molecule of graphene
Compounds
Compounds contain two or more atoms of different elements chemically bonded together
in definite proportions.
Atoms in compounds can form molecules - a network of atoms. Molecule is group of two
or more atoms chemically bonded together.
- Apply the term ‘homogenous’ and ‘heterogenous’ to mixtures
What are the properties of a homogenous mixture?
- uniform composition;
- any sample of mixture is identical to any other sample.
- A solution is homogenous.
Examples of a homogenous mixture
homogonised milk, tap water, sea water, wine, vinegar
what are the properties of a heterogeneous mixture?
- composition that varies within mixture.
- Different components of
mixture can be seen.
Examples of a heterogeneous moixture
fruit cake, salad dressing, soda water, bread, sandy water, cereal in milk
What can happen when a substance is mixed with a solvent?
Can dissolve to form a liquid
but
Substance mixed with solvent does not always dissolve to form solution; it can form
suspension or colloid.
What is suspension?
heterogenous mixture and has distinguishable parts. It forms when
substance does not dissolve significantly.
Examples of suspension
muddy water, red blood cells in plasma
What is a colloid?
mixture of particles that consist of smaller clusters of ions or molecules. It is
evenly dispersed throughout solvent.