Introduction- 3rd Flashcards
what are good observations to make when describing substances in practical work?
- solid, liquid or gas?
- coloured or colourless?
- crystalline or powdered? (for solids)
- clear or cloudy? (for liquids)
what are good observations to make when describing changes in practical work?
- is there any fizzing?
- has a solid appeared or disappeared?
- has anything changed colour?
- are there any unusual sounds or smells?
what are the two categories for changes?
chemical and physical
what are the characteristics of physical changes?
- create no new substance
- are usually easy to reverse
- absorb or release small amounts of energy
name an example of a physical change.
melting ice in a beaker.
what are the characteristics of chemical changes?
- creates new substances
- are usually difficult to reverse
- absorb or release large amounts of energy
name an example of a chemical change.
burning wood on the floor.
what is the chemical test for water?
anhydrous copper(II) sulphate turning from white to blue. this tells us that water is present, but not how pure it is.
what are the two physical tests for water?
melting point (MP) : 0 degrees celcius
boiling point (BP) : 100 degrees celcius
purer water matches these properties more closely.
what is an element?
an element is a substance containing only one type of atom.
name four properties of metals.
- high MP/BP
- electrical conductors
- malleable
- shiny
name four properties of non-metals.
- low MP/BP
- electrical insulators
- brittle
- dull
where are metals found on the periodic table?
on the left-hand side of the staircase.
where are non-metals found on the periodic table?
on the right-hand side of the staircase.
where are diatomic elements found on the periodic table?
3 right including nitrogen, 5 down ( a number 7) + hydrogen
what is a compound?
a compound is a substance containing more than one type of atom, chemical bonded together.
how can compounds be made?
by heating their elements together.
how are the properties of the elements in the compound in comparison to the compound?
the properties of a compound are usually totally different from the properties of the elements the compound is made from.
what are the three types of compound?
metallic, ionic and covalent.
how do you find out the bonding in a compound?
on whether the elements are metals or non-metals
introduction: picture 1
what is used to illustrate diffusion of gases?
making the compound ammonium chloride in a tube
introduction: picture 2
how is the compound ammonium chloride made in a tube?
two gases, ammonia and hydrogen chloride diffuse from the ends of the sealed tube. where they meet, the compound ammonium chloride forms as a white smoke.
looking at the diagram, what does this tell us about the hydrogen chloride molecules? introduction: picture 2
that the hydrogen chloride molecules must be heavier, as they diffused slower.
what would happen if you heated up the ammonium chloride tube?
the white smoke would form faster because particles move faster and collide more often. it still forms in the same place because both gases diffuse faster.
define solute.
the substance which is going to be dissolved.
define solvent.
the liquid which is going to do the dissolving.
define solution.
the resulting mixture of solute dissolved in the solvent.
define saturated.
a solution in which no more solute can be dissolved.
define suspension.
a solid floating in a liquid because it cannot dissolve.
define soluble.
a substance which can be dissolved.
define insoluble.
a substance which cannot be dissolved.
how do we measure solubility?
in g per 100g of solvent.
what does the line of the solubility curve tell us?
the line = saturated
shows the maximum mass of solid which can be dissolved at each temperature.
what does the area below the solubility curve tell us?
below = soluble
less than the maximum mass of solid, so it will all dissolve.
what does the area above the solubility curve tell us?
above = insoluble
more than the maximum mass of solid, so some will dissolve and some won’t. The mass that dissolves can be found by reading off the line.
what are the three states of matter?
- solid
- liquid
- gas
describe the arrangement, movement and energy of a solid.
- regular arrangement, tightly packed
- vibrate in fixed position
- energy : low
describe the arrangement, movement and energy of a liquid.
- irregular arrangement
- particles slide past each other
- energy: moderate
describe the arrangement, movement and energy of a gas.
- random arrangement
- move freely at high speeds in all directions
- energy: high
solid -> gas
sublimation
solid -> liquid
melting
liquid -> solid
freezing
liquid -> gas
boiling
gas -> solid
deposition
gas -> liquid
condensation
how are elements arranged in the periodic table?
in order of atomic number.
what are groups and what are periods?
groups- vertically
periods- horizontally
what is an atom?
atoms are the smallest part of an element.
what is a molecule?
molecules are made up of two or more atoms, they can be formed by two atoms of the same element, or by atoms from two or more different elements.
what is an element?
an element is a pure substance that is made of only one type of atom.
what is a mixture?
a mixture contains two or more different elements or compounds that are not chemically bonded to each other
what is diffusion?
diffusion is the spreading out of particles in a gas or liquid from an area of high concentration to low concentration.
why do elements in the same group of the periodic table have similar chemical properties?
because they have the same number of electrons in the outer shell.
define solubility in units g per 100g of solvent.
the mass of solute which must dissolve in 100g of solvent at that temperature to form a saturated solution.
