Chemistry: Quiz 1 Flashcards
Particle Model of Matter
All matter is made up of small particles called atoms
The particles in a substance are attracted to each other
All particles in a pure substance are the same
There are spaces between particles
Particles are always moving
Mass
Matter is anything that has mass and occupies space
Solids
Particles are tightly packed
Fixed (definite) volume and shape
Particles move very little
Liquids
Particles are farther apart than in a solid
Fixed (definite) volume and changing shape
Particles move around
Gases
Particles are loosely packed
Changing volume and shape
Particles move freely (need a lid for containers)
What are the different ways matter can change state
Solid → liquid: melting
Liquid → solid: freezing
Liquid → gas: vapourizing / evaporating
Gas → liquid: condensing
Solid → gas: subliming
Gas → solid: subliming
Physical Properties
- Can be observed with the five senses
Ex: shape, size, texture, flexibility, boiling point, melting point, state, how hard it is, magnetic, density - When a physical change occurs, the molecules do NOT change
Chemical Properties
- Describes the reactivity of a substance
- How a substance will react to other substances
- A chemical change occurs when you create a new substance
Ex: changes in smell or colour, how easily it catches fire or burns, how it reacts with other substances.
Pure Substance
- All parts that make up the substance are identical
- Its chemical and physical properties are constant
Elements (from the chart)
- It is a substance made up of only one type of atom
- Cannot be broken down into other substances
Compounds
- A chemical combination of two or more elements in a specific ratio
- Elements are held together by chemical bonds
Homogenous
A mixture in which the different substances are NOT visible
Colloid
A mixture in which the suspended substance cannot be separated from the other substances in the mixture
Mixture
- A combination of pure substances
- The proportions in a mixture vary, so the properties of the mixture vary
Heterogeneous
A mixture in which the different substances are visible
Suspensions
A mixture in which the components are in different states
Mechanical Mixture
A mixture in which the different substances are visible
John Dalton
- All matter is made up of small, invisible particles called atoms
- Described atoms as tiny spheres
- All atoms of an element have identical properties such as size and mass
- Atoms of different elements have different properties
- Atoms of different elements can combine to form now substances (compounds)
J.J. Thomson
- Discovered the electron (negative)
- Atom was represented using the “plum pudding” or “raisin bun” model
- His experiments showed that atoms of different elements contained smaller particles that were identical
Ernest Rutherford
- Discovered the nucleus of the atom
- Believed that most of the atom was empty space
- The nucleus of the atom contained protons (positive) and neutrons (neutral)
- The electrons orbited around the nucleus
Niels Bohr
Electrons travel only in specific electron shells or energy levels
Current Atomic Theories
- Each level can be thought of as a cloud of negatively charged electrons
- The electron cloud surrounds a nucleus containing two types of particles (neutrons and protons)
- Electrons are grouped in pairs
Elements
- Substances that cannot be broken down into other substances
- The basic building blocks of all materials
- 90 elements are naturally occuring, others are synthetic (created by humans using nuclear reactors, particle accelerators, or the atomic bomb
Atomic Number
- Number that indicates the amount of protons in a particular element
- The atomic number defines what the element is