Chemistry Topic 1
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what 3 things do atoms contain
atoms contain protons, neutrons and electrons
what does the top number of an element show
the top number shows the total number of neutrons and protons
the number of protons equals the number of what
the number of protons equals the number of electrons
what does the bottom number of an element show
the bottom number shows the amount of protons
what are isotopes
isotopes are an element with the same number of protons but have a different number of neutrons
what makes up the nucleus of an atom
protons and neutrons make up the nucleus of an atom
what is a chemical compound
a compound is when two or more elements join together with a chemical bond
how do you know if a symbol equation is balanced
it is balanced when the same number of atoms are on both sides
balance this equation: Mg + O2 = MgO
2Mg + O2 = 2MgO
What is a chemical mixture
a mixture is there a two or more elements with no chemical bond
what 4 ways are there to separate mixtures
-chromatography -filtration -crystallisation -distillation
what did J J Thomson’s Plum Pudding model show
it showed that electrons were spread about a positively charged “pudding”
what surrounds the nucleus of an atom
shells surrounds the atom’s nucleus
how many electrons are allowed in the first shell
2 electrons
how many electrons are allowed in the second shell
8 electrons
who developed the first periodic table
Dmitri Mendeleev
why did Mendeleev leave gaps in his table
he left gaps for predicted new elements
what are the group 1 elements known as
the group 1 elements are known as the alkali metals
what are the group 7 elements known as
the group 7 elements are known as the halogens
what are the group 0 elements known as
the group 0 elements are known as the noble gases