chemistry
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Which particle determines what element an atom is?
• PROTONS
Which sub-atomic particle does NOT have a charge?
-NEUTRONS
If an atom has 6 protons and 5 electrons, what charge will it have overall?
+1
Which particles within an atom have a relative mass of 1?
PROTONS AND NEUTRONS
Electrons orbit the nucleus in energy …
Electrons orbit the nucleus in energy shells.
What do we call an atom that has a positive or negative charge?
AN ION
An atom has 13 protons and 14 neutrons. What is its mass number?
27
What are isotopes?
Atoms of the same element with different numbers of neutrons
Four atoms have the numbers of protons and neutrons given below. Which two atoms are isotopes of the same element? Atom W: 11 protons and 10 neutrons Atom X: 10 protons and 10 neutrons Atom Y: 9 protons and 9 neutrons Atom Z: 10 protons and 9 neutrons
X AND Z
Lithium naturally exists as two isotopes: lithium-6, with an abundance of 7.6%, and lithium-7, with an abundance of 92.4%.
6.92
When Democritus first conceived of atomic theory, around 500 BC, how did he describe atoms?
• The smallest possible unit of matter • Separated from each other by empty space • Small spheres
In 1897 J. J. Thomson theorised that an atom consisted of a ball of positive charge, with negative electrons mixed throughout it. What do we call this model?
plum pudding model
In the 1800’s, John Dalton described atoms as ….. , and suggested that different types of spheres make up the…. .
• solid sphers • different elelemnts
In Rutherford’s experiments, alpha particles were fired at a thin sheet of gold foil. Most particles passed through, but some were deflected off course. This caused him to hypothesise that there was a dense region of positive charge at the centre of the atom that repelled the alpha particles. As a result he developed the nuclear model of the atom, in which there was a central positive nucleus, surround by negative electrons.
An atom of oxygen has 6 electrons in the outer shell. In a reaction, it gains 2 electrons. What is the charge of the oxide ion created?
2-
definition of isotopes?
isotopes are the same element that have the same number of protons but a different number of neutrons.
smallest element in the periodic table?
hydrogen
what do different isotopes have?
• different masses
how do isotopes react even though they have different number of neutrons?
• they react the same way
how to calculate the relative mass of two isotopes?
sum of abundance of all isotopes
what does it mean when an atom is not stable?
doesnt have a full other shell
what do not stable atoms do?
react with other atoms to become more stable
,eaning of stable in electrons
outermost shell is full
define a group in period table with full outer shell
noble gases have a full outer shell