Size Dependent Properties
Physical Properties
Used to describe a characteristic of matter you can detect with your senses
It can be observed without changing the identity of the material
All matter has physical properties
Color
Shape
Size
Smell
Taste
Mass
Density
volume
Mass = amount of matter in an object
Volume = how much space matter takes up
Density = amount of matter in a given volume
State of matter
Also a physical property
Depends upon temperature and pressure
Size-Dependent and Size-Independent Properties
Some physical properties can change when the size of an object changes = size-dependent properties (volume and mass)
Length, width, and height are also size-dependent
Density does not change with a change in size = size-independent property
Color and state are also size-independent
Physical Properties of acids and bases
Strength of an acid can be found by finding the pH of the acid
Range from 0 – 14
Above 7 = basic
Below 7 = acidic
7 = neutral
Water is neutral
Acids
Sour taste
Some very dangerous (hydrochloric acid)
Some edible – citric and ascorbic acids – vinegar (acetic acid)
Bases
Ammonia common base used in household cleaning
Soap
Bitter taste
Slippery feel
Chemical Properties
Describes how matter behaves
Characteristic of matter that allows it to change to a different type of matter
Choosing matter
Reactivity is how easily one thing reacts with another
Some metals are unsuitable for jewelry
For example, iron is less attractive and less valuable than gold
It is also highly reactive – it rusts easily
Silver and gold on the other hand have less reactivity, and are better choices for jewelry
Chemical Properties of Acids and Bases
Acids and bases have chemical properties that make acids taste sour and bases taste bitter and feel slippery
Acids
Many acids react with or corrode certain metals
Many acids are edible, but many can also damage plant and animal tissue
Nitric acid and sulfuric acid are found in small amounts in acid rain
Acid rain damages structures and buildings slowly over time
lt can also harm plant and animal life
Bases
A strong base is as dangerous as a strong acid
Sodium hydroxide can damage living tissues
Ammonia can cause nose burns or bloody noses
Size Dependent Properties
Salts
Acids and bases react together sometimes forming salts
Salts are compounds made of metal and nonmetal
Table salt – sodium chloride is the most common salt
Formed from hydrochloric acid and sodium hydroxide
Other salts include
Calcium carbonate = chalk
Ammonium chloride = used in some batteries
Physical and Chemical Changes
Physical change = any change in size, shape, form, or state where the identity of the matter remains the same
Chemical = one type of matter changes into a different type of matter with different properties.
Chemical Changes
New materials are formed
Cannot be reversed easily
Signs of chemical changes include: release or absorption of energy
Formation of a gas or a solid that is not a result of change of state
Size Dependent Properties
Physical Changes in Nature
Physical weathering is a physical change that is responsible for much of the shape of the Earth’s surface
Soil comes from physical weathering
Gravity, plants, animals and the movement of the land during earthquakes also cause physicla changes on the earth
Size Dependent Properties
Chemical Weathering
Cave formations form from chemical weathering
Also instances of unnatural chemical weathering – acid rain
Acid rain can chemically weather marble buildings and statues and other outdoor objects.
Size Dependent Properties
