Properties of Matter

Characteristics of a substance

Physical Properties characteristics that can be observed without changing the chemical identity of the substance – Not dependent on amount of sample Appearance Odor Melting Point Boiling Point Density Hardness Texture Ductility/Malleability Solubility Electrical/Thermal Conductivity Magnetism

Chemical Properties Characteristics that describe the ways a substance can react to form new materials – Cannot be observed without changing the chemical composition of the substance Examples Flammability Reaction with Oxygen Reaction with Water Decomposition by light Decomposition by heat Tendency to Corrode

Physical Changes Changes that do not result in the formation of a new substance – Chemical bonds have not been broken or formed; the molecules are still connected in the same way Change of state Change in appearance

Chemical Changes Changes in the chemical bonds of a substance – Always produce a new substance – Chemical bonds are broken and/or formed – Signs: Visible flame Color change Bubbling/Fizzing Smoke Heat/Light given off Formation of a substance in a different state

Kinds of Matter Elements – cannot be broken down into any other substance – All matter is composed of elements. – Each element is made of a specific type of ATOM Ex: Oxygen Ex: Hydrogen

Kinds of Matter Compounds – two or more elements chemically combined in a specific ratio

Kinds of Matter Mixtures – two substances that are together in the same place but are NOT chemically combined

States of Matter Matter is made of tiny particles that are in constant, random motion – can be classified as a solid, liquid, gas, or plasma depending on the motion and arrangement of the particles

Solid Particles do not move freely, but vibrate in place – Packed tightly together, usually arranged in a specific & fixed pattern Definite volume Definite shape

Liquid Particles move freely – Fairly close together, but not in a fixed pattern Definite volume Indefinite shape (take shape of container) – Viscosity: resistance to flow High viscosity – slow flow (honey) Low viscosity – easy flow (water)

Gas Particles move very energetically in all directions – Very fast and far apart Indefinite volume (take up all available space) Indefinite shape (take shape of container)

Plasma Particles have extremely high energy – Highly energetic charged particles that move independently – Extremely fast and far apart Most of the matter in the universe!

Particle Motion Solids – particles tend to move slowly (vibrate) and keep their shape Liquids – particles move freely and take the shape of their container Gasses – particles move excitedly and fill all available space Plasmas – charged particles move extremely excitedly and fill all available space What misconceptions could be created by the model shown here of particles in a solid, liquid, gas, and plasma?

Phase Changes Transfer of heat energy is required to change the state (or phase) of a substance – Freezing/Melting Point – Boiling/Condensation Point Argon Ice melting and sublimating at the same moment

Phase Graphs

Draw your own Phase Graph

Density Density is a measure of how closely packed the atoms are in a substance Density will change as temperature changes – As a substance is heated, particles tend to spread, making it less dense (ice is an exception) – Solids tend to be more dense than liquids; liquids tend to be more dense than gasses.

Calculating Density Density equals mass divided by volume d = m/v – Mass usually measured in grams (g) – Volume either found by displacement or calculated using a formula (mL, cm 3, or cc) Units: g/mL or g/cm 3 or g/cc

Sinking and Floating Density determines whether an object will sink or float. Substances/Objects that are more dense will sink in substances that are less dense. Substances/Objects that are less dense will float in substances that are more dense. – The diet coke is less dense than water. The regular coke is more dense than water. Coke = g/mL Diet Coke = 0.997g/mL Water = g/mL

Conductivity Electrical Conductivity – the ability of a substance to allow electrical energy to flow through it Thermal Conductivity – the ability of a substance to allow thermal energy to flow through it – Both are related to density CONDUCTORS: more dense materials tend to be better conductors (allow energy to flow through them easily) INSULATORS: less dense materials tend to be poor conductors (resist the flow of energy through them)

Special Properties of Water Unlike most substances, the freezing point and boiling point of water allow it to exist as a solid, liquid, and gas at natural Earth temperatures

Special Properties of Water Water heats up & cools down very slowly compared to other substances – Due to a property called “specific heat” – This maintains a moderate environment on Earth that is suitable for life

Special Properties of Water Water forms “polar molecules”, creating “hydrogen bonds” between molecules. This results in… – Cohesion – water molecules attracted to each other – Adhesion – water molecules attracted to other substances

Special Properties of Water Water is called the “universal solvent” – Many other substances dissolve in water The water we encounter is rarely pure because so many minerals can easily dissolve in it.