Chapter two Flashcards
(27 cards)
Atoms consist of
protons, neutrons and electrons
matter
anything that takes up space and can be weight
does light have mass
NO
what is an element
A chemical element is a chemical substance whose atoms all have the same number of protons.
states of matter
solid, liquid, gas
element
substance that cannot be broken down into other substances by chemical reactions
how many natural elements are there
92
Atomic number
number of protons in element
atomic mass
Sum of protons and neutrons
how many elements are essential to humans and plants
Human:25
Plants:17
what four elements make up 96% of the human body
Oxygen, carbon, hydrogen, nitrogen
Trace elements
you cannot live without the 14 trace elements
elements combine to form
compounds, substances that contain two or more different elements in a fixed ratio
substances that contain two or more different elements
Compund
A molecule consisting of atoms of only one element is not
A compound
What is a polar molecule
Has a positive end (hydrogen atoms) and a negative end (oxygen atom) because of the uneven distribution of electrons.
Hydrophilic
Water loving -able to dissolve substances
Hydrophobic
Fear water- does not mix with water (oil)
Isotope
Are forms of an element that differ in mass
Isotope
Proton stay the same but neutron varies
Radioactive isotope
Nucleus decays spontaneously shedding particles and energy
Chemical bonding
Atoms staying close together held by attractions
Chemical bonds
Ionic covalent and hydrogen atoms
Ionic bond
Result from attraction between opposite charges iona
