Science unit 3 deck cards Flashcards
Hypotheses (H)
an educated guess based on observation and inferences, but has not been proved.
Theories (T)
an explanation of a set of related observations based on proven hypotheses that have been verified multiple times by separate groups of researchers.
Laws (L)
a factual statement about a scientific discovery that is accepted to be true and universal.
scientists: Rutherford
atom is made up of a nucleus located in the center of the atom surrounded by electrons. nucleus is very small and contains protons.
scientists: Chadwick
mass of an atom is a combination of the neutrons and protons found in the nucleus.
scientists: Democritus
discovered the atom. atoms are invisible.
scientists: Bohr
discovered neutrons. electrons located further away from the nucleus have higher energy than electrons located closer to the nucleus.
scientists: Thomson
atoms contain negatively charged particles called electrons.
scientists: Dalton
all matter was made up of tiny, invisible, solid objects. his theory is known as the billiard ball model of the atom.
scientists: Aristotle
matter is made of earth, water, and air
what is an atom?
an atom is the smallest unit of an element
who discovered protons? where are they located? positive, negative, or neutral?
Rutherford, located in the nucleus, protons are positive
who discovered electrons? where are they located? positive, negative, or neutral?
Thomson, located on the orbitals, electrons are negative
who discovered neutrons? where are they located? positive, negative, or neutral?
Chadwick, located in the nucleus, neutrons are neutral
what is atomic mass?
protons + neutrons
what is the atomic number?
protons
what is standard atomic notation?
atomic weigh: left top
atomic number: left bottom
chemical symbol: middle
what is the Bohr-Rutherford diagram?
protons and electrons are equal (have the same number)
the atomic number becomes the protons and the electrons
atomic weight minus (subtraction) atomic number becomes the neutrons
what are isotopes?
all atoms of the same element have the same amount of protons
all atoms of the same element can have a different number of neutrons which changes the mass but does not change the charge
example:
carbon-12
6 protons
6 neutrons
carbon-13
6 protons
7 neutrons
carbon-14
6 protons
8 neutrons
alkaline metals
group1, 1 valence electron, shiny, soft, highly reactive
alkaline earth metals
group2, 2 valence electrons, shiny and silvery, not soft or reactive
transition metals
good conductors, solid/liquid, high melting point, high boiling point
halogens
group17, 7 valence electrons, very reactive, solid/liquid/gas, at room temperature
noble gases
group18, 8 valence electrons, stable, unreactive gas, colorless, tasteless, odorless, non-toxic
what is charging by friction?
when 2 objects are neutral and rub together. one object accepts the electrons and one object gives up their electrons.
what is charging by conduction (contact)?
when 2 objects have a different charge and make contact. electrons always move from the more negative object to the less negative object, until they have the same net charge.
what are conductors?
materials that allow electrons to move freely on or through them. ex: metals
what are insulators?
materials that hold onto their electrons, electrons don’t move and they can build a static charge. ex: non-metals
what is grounding?
objects with an excess electric charge (+ or -) remove their charge by transferring electrons between to a large neutral object.
what are lightning rods?
metal pole that is attached to a wire that runs into the ground
what is the Big Bang theory?
the theory that all of the matter and energy in the universe expanded from a single point.
how are stars formed?
gravity pulls nebulas together and when pressure is high enough elements fuse together creating a star
what was the first star formed from?
the first star was formed from a nebula (cloud of gas and dust) of hydrogen atoms that clumped together
for stars what colors mean hot and cold?
RED is COOL
BLUE is HOT
for stars what does size mean?
SMALL is PLANET SIZE
LARGE is SUN SIZE
what is the pathway for low-mass stars?
nebula - protostar - red dwarf - white dwarf
what is the pathway for medium-mass stars?
nebula - protostar - red giant - planetary nebula - white dwarf - black dwarf
what is the pathway for large-mass stars?
nebula - protostar - red supergiant - supernova - neutron star - black hole
how was the solar system formed?
Our solar system formed from a nebula of dust and gas that began to contract from gravity.
what is the carbon cycle?
Carbon is recycled in the carbon cycle through
photosynthesis and respiration.
stages:
1. carbon moves in the form of CO2, from the atmosphere to plants on the land and in the ocean
2. carbon moves from plants to animals
3. carbon moves from animals to the ground
4. carbon returns to the atmosphere
why is nitrogen important?
nitrogen is necessary for protein and DNA formations in organisms
what are the stages of the nitrogen cycle?
the process that describes how nitrogen enters and leaves the atmosphere through a complex pathway that involves many different types of bacteria.
stages:
1. nitrogen enters the soil from the atmosphere
2. nitrogen moves up the food chain
3. nitrogen is excreted and enters back into the ground
4. nitrogen enters back into the atmosphere
how do humans impact the nitrogen cycle?
humans add nitrogen to the soil as fertilizers to help plants grow
law of electric charge: what do opposites do?
attract
law of electric charge: what happens if they like each other?
repel
