Studied by 4 people
elements
a pure substance that cannot be broken down into other substances
what are the four elements?
oxygen, carbon, hydrogen, nitrogen
how much living matter in the body do elements make up
96% of the human body
trace elements
needed for the body in small amounts. insufficient amounts can cause health issues
compounds
a substance containing 2 or more elements that are chemically combined in a fixed ratio
list the four most abundant elements in your body
oxygen 65%, carbon 18.5%, hydrogen 9.5%, nitrogen 3.3%
how are elements and compounds different?
elements are individual while compounds are multiple elements
atoms
smallest possible particle of an element
what are the 3 subatomic particles and what are the charges
protons- positively charged. electron- negatively charged. neutron- no charge
where are protons and neutrons located
in the nucleus
where are electrons located
they move around the nucleus
atomic number
the number of protons in an atoms nucleus
isotopes
alternate form of an element. they have the same number of protons but different electrons
radioactive isotopes
has a nucleus that decays or breaks down. used in research and medicine. releases radiation in the form of matter and energy
most often the electrons in the highest energy level…
determine how the atom reacts
how many electrons are in the 4 elements
H- 1 electron. C- 6 electrons ( 4 in 2nd lvl.) N- 7 electrons (5 in 2nd lvl). O- 8 electrons ( 6 in 2nd lvl)
partially filled energy levels result in?
chemically reactive atoms
atoms that are fully filled…
are not chemically reactive
chemical bonds..
join atoms to one another
ionic bonds
chemical bonds that are formed when 1 atom transfers an electron to another atom
covalent bonds
forms when 2 atoms share electrons
what are the number of bonds
the number of bonds an atom can form tends to equal the number of electrons it needs to fill its highest energy lvl
molecules
formed by 2 or more atoms joined by covalent bonds
chemical formula
shows the type and number of atoms in a molecule
methane
CH4
propane
C5 H8
butane
C4 H10
chemical reactions
involve breaking or forming chemical bonds
chemical equations
used to describe reactions. shows reactants and products
how is potassium atom different from potassium ion
the ion has lost an electron giving it a positive charge
Note 
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