Concepts of Science 2
Terms
undefined, object
copy deck
- Dalton
- hypothesized that for every chemical element there is a corresponding species of objects called atoms; element is a substance that cannot be broken down into other substances.
- Molecule
- Any cluster of atoms that can be isolated.
- Electrolysis
- "splitting be electricity" was developed in the early 19th century. and this allowed rapid discovery of many elements.
- Earths composition
- 99% made of 6 elements- Oxygen(o), Silicon(Si), Magnesium(Mg), Iron(Fe), Aluminum(Al), and calcium(Ca)
- Living Organisms Composition
- 90% made of 6 elements- hydrogen(H), carbon(C), nitrogen(N), oxygen(O), phosphorous(P), Sulfur(S)
- Stars Composition
- Hydrogen(H) and Helium (He)
- Thompson
- identified a subatomic particle called the electron
- Rutherford
- experimented with gold foil that was penetrated by subatomic particle radiation: scattering and reflection of radiation proved the existence of a dense center of gold atoms: the nucleus
- Nucleus has two types of particles
- proton and neutron
- Life expectancy for Rutherford atom
- 1 second
- Bohr
- said electrons exist in various levels or shells located about the nucleus; each shell corresponds to an energy level of the electron
- Ground state of atoms
- all electrons in lower energy levels
- Excited state of atoms
- some or all electrons are in the highest energy levels
- Photon
- a packet of energy with a paradox; both a particle and a wave
- Quantum leap
- electron must dissapear at one level and reappear at another level without transversing the distance.
- spectrum
- total collection of photons emitted by a given atom, therefore each has a unique spectrum.
- spectroscopy
- study of elemental composition using absorption lines.
- Atomic number
- defines the sequence of elements in the table; number of protons in nucleus.
-
Alkali earths
Alkalie metals
Noble gasses -
first column
second column
eigth column - Valence electron
- Electrons in outer shell
- chemical bonding
- commonly involves exchange or sharing the valence electron.
- Valence
- number of electrons in the outer shell
- inert gasses
- most stable arrangement of lowest energy because all shells are filled completely with electrons
- Quest of the atom
- to acheieve the lowest energy state it can. so when atoms come near each other they may exchange or share electrons to acheieve this state.
- chemical bonds
- result of redistribution of electrons that leads to a more stable configuration btwn. two or more atoms
- Ionic bonds
- atoms with one less or one more than the noble gas number of atoms.chemical bond in which the electrical for between two oppositely charged ions hold the atoms together.
- Alloy
- combined metals
- Carbon Bond
- the basic bond of all essential molecules of life on earth.
- Organic chemistry
- study of C bonding and related bonding
- Polar molecules
- molecules with either a positive or a negative side.
- hydrogen bonds
- weak electrical attraction developed by the H atoms itself after it is bonded to another element.
- Plasmas
- seas of electrically charged particles at very high temps.
- Crystals
- groups of atoms that occur in a regularly repeating sequence forming a structure in which atoms or molecules occur in a regular and predicatable way.
- crystalline solids
- composed of interlocking crystals
- Polymers
- long and large molecules that are formed from numerous smaller molecules.
- Plastics
- made of intertwined polymers derived from petroleum
- Liquid crystals
- an odd intermediate state of matter that is half way between liquid and crystalline solid.
- sublimation
- change from solid to gas
- Chemical reactions
- atoms and molecules coming together to form larger structure or larger structures breaking apart. the rearrangement of atoms or molecules in chemical compounds.
- Reduction
- chemical reaction in which electrons are transferred to an atom from other elements.
- Acid
- any material when put in water produces positively charged H ions in the solution
- Base
- any material when put in water produces negatively charged OH ions
- Acid-base reaction
- when two are brought together, water is formed
- diameter of atom
- 100,000 times the of the nucleus
- Nuclear system
- what goes on in the electron shells is essentially independent.
- Energy of nuclear system
- energy of the nucleus is far greater than the energy of the electrons.
- Mass number
- total number of protons number of nucleus in nucleus
- isotopes
- atoms withe different number of nuetrons but same number of protons
- radiation
- emitted particles of radioactive decay
- stable isotope
- an isotope that is not radioactive
- Becquerel
- discovered and studied radioactivity by using photographic plates that were exposed by unseen radiation
- Alpha decay
- emission of a massive sub-atomic particle consisting of 2 protons and 2 nuetrons
- Beta decay
- emission of an electron and simultaneous creation of a massless neutrino particle.
- Gamma radiation
- emission of an energetic photon, electromagnetic radiaiton this is produced by reshuffling of particles in the nucleus.
- Ionization
- stripping away of electrons by violent interaction and alpha and beta particles.
- Half-life
- average time that it takes for half of a gtroup of radioactive isotopes to undergo radioactive decay
- keck-type telescope
- uses multiple mirrors over a large area in order to achieve the effect of a very large mirror size
- luminosity
- total energy emitted by a star
- Leavitts theory of cephid variables
- absolute brightness is related to time length of bright dim cycle. therefore if we know relative brightness we can figure distance
- Hertzsprung- russell diagram
- graphical way of finding order among stars
- star formation
- nubular spin and collapse due to gravity causes. central mass becomes a star and the disk of gas and dust becomes the collection of planets at critical size
- Neutron star
- all that remains at the core of a supernova explosion