CMH 101 Luca Preziati

Chapter 2: Matter and Energy

DEFMatter = anything that occupies space and has mass

H2O

H2O

H2O

H2OH2O

H2O

< Particulate

Macroscopic > < Symbolic

In Chemistry, Biochemistry and Molecular Biology matter can be observed as a macroscopic or microscopic entity, imagined at the particulate level and represented using symbols

Atoms are the tiny particles that make up all matter.

In most substances, the atoms are joined together in units called molecules

Chapter 2: Matter and Energy

States of Matter

State Shape Volume Compress Flow Solid Fixed Fixed No No

Liquid Indef. Fixed No Yes

Gas Indef. Indef. Yes Yes

Chapter 2: Matter and Energy

< Chemical Properties are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy (chemical reaction)

< Physical Properties are the characteristics of matter that can be changed without changing its composition (no chemical reaction)

Chapter 2: Matter and Energy

• Pure Substance = all samples are made of the same pieces in the same percentages– salt

• Mixtures = different samples may have the same pieces in different percentages. Separate into components based on physical properties– salt water

Pure Substance

Constant Composition

Mixture

Variable Composition

Matter

Homogeneous HeterogeneousElements CompoundsIdentical atoms Different atoms One phase Multiple Phases

Chapter 2: Matter and Energy

Chapter 2: Matter and Energy

The Electrical Character of Matter

Two Kinds of Charge called + and –

Opposite Charges Attract+ attracted to –

Like Charges Repel+ repels +– repels –

To be Neutral, something must have no charge or equal amounts of opposite charges

Chapter 2: Matter and Energy

Law of Conservation of Mass

Antoine Lavoisier

“Matter is neither created nor destroyed in a chemical reaction”

• the total amount of matter present before a chemical reaction is always the same as the total amount after

• the total mass of all the reactants is equal to the total mass of all the products

Chapter 2: Matter and Energy

Energy

DEFEnergy = anything that has the capacity to do workLaw of Conservation of Energy:“Energy can neither be created nor destroyed”

Kinetic Energy is energy of motion, or energy that is being transferred from one object to another

Potential Energy is energy that is stored

We cannot get a 100% efficient energy transformation process

Chapter 2: Matter and Energy

The Conservation Law

E = mc2

Energy = mass x speed of light2

Albert Einstein realized that it is also possible to transform matter in energy and vice versa. This transformation mainly happens in nuclear reactions where a tiny amount of matter in converted into an enormous amount of energy