Topic 1: Stoichiometry Flashcards
What is a molecule?
Two or more atoms connected by chemical bonds, which form the smallest unit of a substance that retains the composition and properties of that substance
What is an ion?
An atom or molecule where the total number of protons is not equal to the total number of electrons.
What are the characteristics of matter?
- made up of particles: atoms, molecules or ions
- particles are in constant motion
- occupies a volume in space
- has a mass
For solids, liquids and gases, outline:
- fixed volume?
- fixed shape?
- compressible?
- strength of forces between particles?
- yes, yes, no
- yes, no, no
- no, no, yes
- strong, weak, (almost) none
What does the vibration and movement of particles depend on?
Temperature
The average kinetic energy increases as the ___________ increases.
Temperature
What are the SI units for temperature?
Kelvin (K)
What is meant by absolute zero (and what is its value)?
The temperature at which all movement of particles stops (-273°C or 0K)
How do you convert temperature (°C) into temperature (K)?
Temperature (K) = Temperature (°C) + 273
How is a change in state caused?
When the temperature increases/decreases, the average kinetic energy of the particles does the same, resulting in a change in state
Which changes of state are exothermic?
Condensing and freezing as energy is transferred to environment
Which changes of state are endothermic?
Melting and boiling as energy is transferred from environment
Does the temperature change whilst changing state?
There is no change in temperature when changing state as the energy is used to break/form bonds
What is the change of state for solid to:
- liquid
- gas
- melting
- sublimation
What is the change of state for liquid to:
- solid
- gas
- freezing
- boiling
What is the change of state for gas to:
- solid
- liquid
- deposition
- condensing
What is matter?
Any substance that occupies space and has a mass
What is a mixture?
A combination of two or more pure substances that retain their individual properties
What is a pure substance?
A substance with a definite and constant composition
What is an element?
A substance made up of atoms that each have the same atomic number
What is a compound?
A substance made up of a combination of atoms or ions chemically bonded together
What is a homogeneous mixture?
A mixture that has both uniform composition and properties throughout
What is a heterogeneous mixture?
A mixture that has non-uniform composition and varying properties
What is an anion?
A negatively charged ion
What is a cation?
A positively charged ion