Chemistry And Physics Gr.10 June Flashcards
What is a pulse?
A single disturbance through a medium.
What is amplitude?
The maximum disturbance of a particle from its rest position.
What is a transverse pulse?
A vibration causes particles of a medium to move at right angles to the direction of propagation of the pulse.
What is superposition of pulses.
The addition of the disturbances of the two pulses that occupy the same space at the same time.
What is constructive interference?
Two crests/ troughs meet and their amplitudes reinforce each other and the total amplitude is the sum of the individual amplitudes.
What is destructive interference?
One crest and one trough meet and cancel each other out if they have equal amplitudes.
What are transverse waves?
A succession of transverse pulses in the medium travel at right angles to the direction of propagation of the wave.
What term describes the motion of particles in a medium when a wave passes them?
The particles oscillate
What is a wavelength?
The distance between two consecutive points that are in phase.
Measured in metres.
What is a period?
The time it takes for one full cycle.
Measured in seconds.
What is a frequency?
The number of vibration cycles per second.
Measured in Hertz.
Who discovered that atoms contain protons and electrons?
Thomson
Who discovered that electrons move in electron clouds?
Schrödinger
Who discovered that elements are made from atoms?
Dalton
Who discovered that electrons move around nuclei in orbits and energy levels?
Bohr
Who discovered that atoms consist of mostly empty space?
Rutherford
What did Schroedinger discover?
Electrons move in electron clouds.
What did Dalton discover?
Elements are made from atoms
Atoms of the same element are the same
Atoms can form compounds
Atoms can’t be created/ divided destroyed
What did Broglie discover?
Electrons have wave-like properties.
What did Thomson discover?
Atoms contain positive and negative particles.
Negative particles are embedded in a positively charged area
What did Bohr discover?
Electrons move around the nucleus in orbits/shells and energy levels
Electrons have amounts of energy
What did Rutherford discover?
Atoms consist mostly of empty space
Protons exist in the centre of atoms
Electrons around the outside
What experiment did Rutherford use to prove that atoms consist mostly of empty space?
The gold foil experiment.
Why are electrons not used to calculate atomic mass?
Their mass is so small that it’s NEGLIGIBLE.
What is relative atomic mass?
The average mass of all the atoms of that element, taking into account all the isotopes.
What is electron configuration?
The way electrons are arranged around the nucleus.
What are two states of electrons?
Excited state and ground state
What happens when an excited electron falls back to its ground state?
The same energy as what was absorbed is released as light.
What are core electrons?
The number of electrons in the inner energy level of an atom.
What are the electrons in the last energy level of an atom called?
Valence electrons
What are ions?
Charged particles
Give another name for group 1 and give its chemical properties.
Alkali metals
Low densities, good conductors, alkaline solutions in water, react with water
Down group: hardness decreases, mpt decreases, reactivity increases
Give another name for group 2 and give its chemical properties.
Alkali earth metals
Less reactive than group 1, silvery, alkaline solutions in water, form solid oxides
Down group: reactivity increases
Give another name for group 17 and give its chemical properties.
Halogens
Diatomic, low mpts and bpts
Down group: reactivity decreases, mpts/bpts increase
Give another name for group 18 and give its chemical properties.
Noble gases
Unreactive
Down group: bpts decrease
What is the name of the middle block of the periodic table?
Transition metals
Give another name for groups 1 and 2
The s-block
Give another name for groups 13-18
The p-block
What is valency?
The number of electrons that an atom must gain, lose or share to achieve the stability of a noble gas.
What is density?
The type of bonds between the atoms of an element determines the density of an element at room temperature.
What pattern does the periodic table show for density?
Density increases down a group
What pattern does the periodic table show for mpts and bpts?
For metals: increases across periods
For non-metals: decreases across periods
C and Si have very high mpts and bpts
What is an atomic radius?
The distance between the nucleus and the last orbital
What pattern does the periodic table show for atomic radius?
Increases down group
Decreases across period
What is ionisation energy?
The amount of energy required to remove an electron from a neutral atom.
Which group has the highest ionisation energy?
Noble gases
What pattern does the periodic table show for ionisation energy?
Increases across period
Decreases down a group
What is electron affinity?
The ability of an atom to accept one or more electrons. (Know but not part of def.: Metals lose electrons and non-metals gain electrons when they react)
What pattern does the periodic table show for electron affinity?
Increases across a period
What is electronegativity?
The tendency of an atom to attract electrons towards itself and form a negative ion.
What pattern does the periodic table show for electronegativity?
Increases across a period
Decreases down a group
What are the colours of the following elements?
Fluorine
Chlorine
Bromine
Iodine
Fluorine. Yellowish
Chlorine Greenish
Bromine. Brown-orange
Iodine Purplish
What is ionic bonding?
When one or more electrons are transferred from a metal atom to a non-metal atom.
What do you call a:
Metal that forms an ion?
Non-metal that forms an ion?
Metal that forms an ion: cation
Non-metal that forms an ion: anion
What do you call the structure that ions are packed into?
A crystal lattice
What holds ions together?
Electrostatic forces
Why do ions have high melting points?
Their electrostatic forces are very strong. It takes a lot of energy to overcome these forces.
What is metallic bonding?
Maybe double check def. by looking in text book
The chemical bond between atoms of the same element.
In metallic bonding, what surrounds the positive atomic nuclei (kernels)?
A sea of delocalised electrons
What is the difference between relative molecular mass and relative formula mass?
Relative molecular mass-molecular compound
Relative formula mass-ionic compound
What is wave speed?
The distance a wave travels in a certain amount of time.
