Elements of the periodic table Flashcards
What is nanotechnology? what are examples?
- the science and technology of the manipulation of the structure of matter at a molecular level.
- Nanoechnology is concerned with very small things measured in nanometers.
- Sunscreen, computers and mobile phones utilise this and it could help with disease treatment and computer efficiency.
what is the nanometre?
1 billionth of a metre or 10 to the power of -9. It is the size of six carbon atoms.
what does the nanoscale describe?
things about 1-100nm wide (eg. DNA 2nm wide)
how do you convert to nanometers?
convert to meters and then to nanometers by multiplying by either 10^9 or ^-9
how can a material be classified as a nonmaterial?Examples? How are they different to materials in bulk?
- they must have one dimension less than 100nm eg. nano layers, nanowires or nanotubes
- they have different properties
what is a nanoparticle?
a type of nonmaterial that is usually spherical and has a diameter less than 100nm
how can nanoparticles be used?
to catalyse, the surface can adsorb (attach) to different molecules and transport molecules around the body, can be used in medicine, cancer treatment, computer storage etc.
what are risks of nanoparticles?
they can travel through skin into the bloodstream and into cells. they can cause unwanted chemical reactions in the body and no one knows what they do and the long term effects
what is atomic theory?
the best explanation but it can change and develop
who presented the first atomic theory? when? what was it?
in 1802, John Dalton.
- He proposed that all matter was made up of small spherical particles that are invincible and indestructible.
- elements are made of one type of atom and compounds, many to fixed ratios
- elements could not be broken down
how was dalton wrong?
that elements could not be broken down. WE now know they have subatomic particles
what is a molecule?
when non-metals combine together. many gases are diatomic molecules (O2)
what are monatomic atoms?
noble gases exist as individual atoms because they are chemically inert
when is a molecule known as as a compound?
if it is made up of two or more different elements
how many elements occur naturally?
around 92
what 5 ways can elements get symbols?
first letter, first letter and another letter, first two letters, Latin name, from other languages
nucleus
made up of protons and neutrons (nucleons)
protons
positive
neutrons
neural
electrons
negative
how much lighter is an electron than a proton or neutron?
1800 times
how much of the atoms mass does the nucleus take up?
99.97%
what did Ernest Rutherford propose and when? (4)
- most mass and all + charge is located in a central region
- most volume is empty space occupies by electrons
- electrons circle the nucleus
- the force between the nucleus and electrons is electrostatic
- 1911
What was Rutherford’s experiment to prove? what did he do? What did he conclude?
- wanted to prove Thomson’s plumb pudding model correct
- fired alpha particles (+) from a radium at thin gold foil
- the paths of particles were determined by bursts of light produced on the screen behind the foil
- most particles went through
- 1 in 8000 deflected and one bounced back
- conc: most of an atom is empty space and the alpha particles bounce back when repelled by positive matter
What did James Chadwick discover? What did he propose? when?
- identified the neutron
- proposed that the nucleus also contained neutrons which explained isotopes
what is an isotope? properties? example?
- same number of protons but differing number of neutrons
- they have identical chemical properties but different physical properties (mass and density)
- every atom has isotopes
- C-14 breaks down into another atom (radioactive)
what is an ion? what are the different types?
- result of atoms gaining or losing electrons
- cation +
- anion -
what colour dow potassium produce?
lilac
what colour does lithium produce?
red
what colour does barium produce?
yellow-green
what colour does calcium produce?
orange-red
what colour does copper produce?
blue-green
what colour does strontium produce?
scarlet
what colour does sodium produce?
orange
why do some metal ions produce a colour if heated?
- when heated electrons can gain energy and jump to higher energy levels
- this makes them energetically unstable so they fall back, releasing light energy
do all atoms produce electromagnetic energy if heated? how can it be seen?
yes. if the light is passed through a prism onto a screen, an emission spectrum is obtained
what is a spectrum?
a series of lines on a black background
What are emission spectra?
they are related to the structure within an atom and each one has a unique spectra
what did Bohr propose and when?
- that electrons circled the nucleus in fixed shells
- shells closer to nucleus have lower energy and those furthest have high energy
- electrons move in orbitals
- heating an element can cause can cause the electron to gain energy and jump to another level
- it then returns to ground state, releasing energy
- they can do this in a number of ways and this produces different colours