Science 1.1, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 Flashcards
what are elements?
elemnts are substances made up of just one type of atom
what are molecular elements?
molecular elements are made up of multiples of the same non-metal atom
what are compounds
Compounds are substances made up of different types of
atoms.
protons = positive
electrons= negative
neutrons= no charge
no ans js memorise
what is a cation?
when an atom has more protons than electrons, it is called a cation (loses electrons)
what is an anion?
when an atom has more electrons than protons it is called an anion (gains electrons)
what is an isotope?
Atoms that have the same number of protons but a
different number of neutrons.
what is a radioisotope?
An unstable isotope that releases radiation as it decays
and becomes more stable.
what is a nuclear reaction
a process that causes a nucleus to change
what is nucleas radiation
rays or particles that are emitted by a nucleus during a nuclear reaction
what are the three types of nuclear decay?
-alpha particles (a)
-beta particles (b)
-gamma rays (y)
alpha decay points?
-α-particles are relatively heavy and move slowly
-the nucleus of a very heavy radioisotope ejects an alpha (α) particle.
-has a 2+ charge
beta decay points?
-The nucleus ejects a beta (β) particle.
-β-particles are identical to electrons,
-negatively charged
-Blocked by a sheet of Aluminium
-A neutron is converted into a proton
gamma decay points?
-Nuclei do not emit a particle, but emit rays
-Occurs when a nucleus is in an excited state and has too much energy to be stable.
-No charge
-Only a thick layer of concrete and lead can block the radiation.
what is a half-life?
Half-life: time it takes for half the nuclei to decay.
what is the half life of carbon 14?
5730 years.
radiocarbon dating
The half-life of radioisotopes of carbon-14 is used by
scientists to determine the age of fossils.
what is the conservation of matter law?
Matter (atoms) cannot be created nor destroyed.
what is an ionic bond?
an ionic bond is when a bond forms between a non-metal and a metal.
what is a covelant bond?
forms between two non metals, and it is when two atoms share one or more pairs of electrons.
what is a metallic bond?
forms in a metallic substance
what are exothermic reactions?
Reactions that release energy into
the surroundings.
● The reactants have more stored
chemical energy than the products
● Typically chemical bonds are being
broken (releasing energy)
what are endothermic reactions?
Reactions that absorbs energy from the
surroundings
● The products have more stored
chemical energy than the reactants
● Typically chemical bonds are being
formed (requiring energy)
what is combustion?
combustion is the scientific term for burning- it requires heat, fuel and oxygen to occur.
Combustion happens when something
quickly reacts with oxygen
