Unit 1 Chemical Changes and Structures Flashcards
What is the relative Atomic Number?
The average mass of the isotopes of an element
e.g
copper-63 & copper-65
R.A.M is 63.5
copper-63 is most abundant
Signs of a chemical reaction
- change of colour
- effervescence
- temperature change
- precipitation
- release heat (exothermic / endothermic)
What is an isotope?
An element with the same atomic no but different mass no due to a difference in nutrons
What are factors that affect reaction rates?
- Temperature - higher temp = faster reaction
- concentration - higher conc = faster reaction
- Particle size - smaller particles = faster reaction
- Catalyst - speeds up reaction - left unchanged
Properties of covalent molecular compounds
- Low melting & boiling points
- Only between non metals
- Do not conduct electricity
- Weak forces of attraction
What are the 4 molecular shapes?
- Linear
- Trigonal Pyramidal
- Angular
- Tetrahedral
properties of ionic compounds
- High melting & boiling points
- Between both metals & non metals
- Conducts electricity in liquid form
- Strong forces of attraction
- water soluble
What is a covalent bond?
A shared pair of electrons between 2 positively charged nuclei
there are Strong covalent bonds inside molecules and weak forces of attractions between molecules
What are diatomic molecules?
diatomic molecules are molecules containing only two atoms
What are the diatomic elements?
- Hydrogen H2
- Florine F2
- Iodine I2
- Nitrogen N2
- Oxygen O2
- Chlorine CL2
- Bromine Br2
What is nuclide notation
a representation of an element that shows mass no, atomic no , and symbol
H+ & OH- concentration in acids and alkalis
Acids = H+ > OH- conc
neutrals = H+ = OH- conc
Alkalis = H+ < OH- conc
what douse pH mean?
pH stands for power of hydrogens and is a measure of H+ concentration
What are ions?
Atoms that have either gained or lost electrons trough the process of ionisation
What happens to non metals during ionisation?
they gain electrons
