elements of life Flashcards
What are isotopes?
Atoms with the same number of protons but different numbers of neutrons.
What was Dalton’s model of the atom?
A solid sphere.
What was JJ Thomson’s model of the atom?
The plum pudding model: a positively charged sphere with embedded electrons.
What was Rutherford’s contribution to atomic theory?
Fired alpha particles at gold foil; some reflected, suggesting a dense nucleus.
What are the 4 principles of the Bohr model?
- Electrons exist in fixed orbits. 2. Shells have fixed energy levels. 3. Electrons absorb/emit energy when moving between shells. 4. Radiation has a fixed frequency.
What are the stages of mass spectrometry?
- Vaporisation 2. Ionisation 3. Acceleration 4. Detection.
What is measured in mass spectrometry?
Time taken to reach the detector; lighter, highly charged ions arrive first.
What is a mole?
6.022 × 10²³ particles (Avogadro constant).
What is the formula for moles?
Moles = mass / Mr.
What are ionic equations?
Equations showing only the reacting particles and products formed.
What is the empirical formula?
The simplest whole number ratio of atoms in a compound.
What is water of crystallisation?
Water chemically bonded in hydrated compounds that is lost when heated.
What is the formula for percentage yield?
(Actual yield / Theoretical yield) × 100.
What is a standard solution?
A solution of known concentration.
How do you dilute a solution?
Final conc. / Initial conc. × Volume of new solution.
What is the purpose of a titration?
To determine how much acid is needed to neutralise an alkali.
What colour change is shown by methyl orange in titration?
Red (acid) to yellow (alkali).
What colour change is shown by phenolphthalein in titration?
Colourless (acid) to pink (alkali).
What are the subshell capacities for s, p, d, and f?
s = 2, p = 6, d = 10, f = 14.
What is spin pairing?
Two electrons in the same orbital spin in opposite directions.
What shapes are s and p orbitals?
s = spherical, p = dumbbell shaped.
What are the s, p, and d blocks?
s-block: groups 1–2, p-block: groups 3–8, d-block: transition metals.
What is ionic bonding?
Electrostatic attraction between oppositely charged ions.
What is the structure of ionic compounds?
Giant ionic lattice; conduct electricity when molten or dissolved, high melting points.