Chapter 1 Flashcards
What is an hypothesis ?
It’s a tentative explanation or prediction in accord with current knowledge
In chemistry we use _________ and __________ type of information.
quantitative and qualitative
What is quantitative informations ?
numerical data
What is qualitative informations ?
non-numerical observations
what is a theory ?
It’s a well-tested, unifying principle that explains a body of facts and the laws based on them
what are the goals of sciences ? (4 goals)
o prediction
o control
o understanding
o explaining
What is a state of matter ?
An easily observed property of matter that is, whether a substance is a solid, liquid or gas.
Characteristics of solid (state of matter)
-Particle are packed closely together
-Hard
-Little volume change with changes of temperature
Characteristics of liquid (state of matter)
-Particles are arranged randomly
-They are not packed
-They can move past one another
Characteristics of gas (state of matter)
-Particles are far apart
-Move extremely rapidly
-Not constrained by their neighbours
-Volume and pressure change dramatically with temperature changes
what is the energy of motion?
Kinetic energy
The kinetic energy is responsible of…….
The temperature
Kinetic energy: In the solid state the particles ….(3 answers)
- are packed closely together
- vibrate around their average position
- Very low compressibility
Kinetic energy: In the liquid state the particles ….(4 answers)
- are oriented randomly
- occupy a little more space than the solid state and they keep moving relative to one another
- still stay close to one another
- Very low compressibility
Kinetic energy: In the gaseous state the particles ….(3 answers)
- are far apart
- move fast in a linear motion until they collide with another particle when kinetic energy is exchanged and direction of motion changes
- Very high compressibility
What is a pure substance ?
- Has a set of unique by which which it can be recognized
- It cannot be separated into 2 or more different species by any physical technique at ordinary temperature
What is a mixture?
Consist of 2 or more substances that can be separated by physical technique
What is a heterogenous mixture?
Can be detected by the naked eye
What is a homogenous mixture?
-2 or more pure substance in the same phase.
-Often called solution
What is an element?
substances that are composed of only one type of atom
What is a compound?
A compound is 2 or more different element held together by chemical bonds.
What are the 2 main differences between an element and a compound?
- A compound has distinctly different characteristics from its parent element. An element is only composed of one type of atom.
- Compound has a definite percentage (%) composition (by mass) of its combining element. An element has 100% composition of his type of atom.
What is physical properties?
are properties which can be observed and measured without changing the composition of substances
Give at least 4 physical properties. The answer has 10 properties.
o colour o state of matter o melting point o boiling point o density o solubility o electric conductivity o malleability o ductility o viscosity
