Elements, compounds, and mixtures revision Flashcards
Element
pure substances made up of one type of atom.
Compound
A substance with two or more different types of atoms that are chemically bonded together
Pure substance
A substance made up of one type of particle. It cannot be physically separated. It can exist as either a compound or an element
mixture
A substance formed by physically mixing two different substances, and can be physically seperated
Where do elements occur on periodic table
in order of increasing atomic number
What are the vertical columns and horizontal rows on periodic table
vertical columns: groups
Horizontal rows: periods
different ways elements occurs:
single atoms, molecules, lattices
molecule:
cluster of two or more atoms bonded together
lattice
grid like structure
how many elements are there and how many occur naturally?
118 known elements, 91 occur naturally
monatomic substance
single atom
atomic number =
number of protons in a nucleus
atomic mass =
protons + neutrons
ductile
can be stretched into wires
malleable
can be bent and hammered into sheets
brittle
breaks easily when force is applied
why do metallic elements bend while non metallic elements break
in metallic elements, the atoms can move around without breaking the metal lattice, while in non metallic elements, the atoms are fixed rigidly in position
subatomic particle
a particle smaller than an atoms. these are electrons, protons, and neutrons.
protons
A subatomic particle with a positive charge
neutron
A subatomic particle with no charge and a mass nearly equal to a proton
electron
A subatomic particle with a negative charge with almost no mass. located in electron cloud
protons + neutrons =
atomic mass
number of protons in an atom =
atomic number
Atom
The smallest part of a substance that cannot be broken down chemically
Chemical bond
An attractive force that holds atoms together.
Symbol
One or two letters used to represent an element
Alloy
Metallic substance made up by mixing a metal and another substance
molecular atom
A molecule made up of the same atom
What property of an atom determines what element it is?
Number of protons
features of metalloids
Metalloids:
conduct electricity,
conducts heat,
lustrous,
malleable,
ductile,
solid at room temp
features of non metals
non metals:
dull,
solids, liquids (1), gasses room temp,
poor conductors of heat or electricity,
brittle
Electrical charge (charge of an atom and why)
Atoms have a neutral charge because there is an equal number of protons and electrons
