Atomic Structure & The Periodic Table Flashcards
How many different elements are there?
There are about 100 elements for which all substances are made.
What is the periodic table?
The periodic table is a list of elements
What is each element made out of?
Each element is made out of one type of atom.
What are atoms represented by?
Atoms are represented by chemical symbols.
What are elements in the periodic table aranged in?
Elements in the periodic table aranged in columns, called groups.
The elements in a group usually have similar proporties .
What do atoms have?
Atoms have a tiny nucleus surrounded by electrons
What happpens when elements react?
When elements react, their atoms join with atoms of other elements.
When are compounds formed?
Compounds are formed when two or more elements combine together.
What is a reactant?
the substance you start with.
What is a product?
the new substance made.
what do chemical eqations show?
Chemical eqations show the reactants and products.
What is a word equation?
give the name of the reactants and products only.
What happens in a chemical reaction?
the atoms are rearrange
What does symbol equations show?
Symbol equations show the numbers and types of atoms in the reactants and products.
Can atoms can be destroyed?
Atoms are neither be created nor destroyed in a chemical reactions.
So the number and type of atoms remains the same before and after the reaction.
What should you do when writing symbol equations?
When writing symbol equations you should always balance the equation.
what does a balance has?
A balanced symbol equation has the same number of each type of atom on both sides of the equation.
what are the multipliers?
numbers placed in front of formulae
What are multiplier used for?
Use multipliers to ensure symbol equations balance.
What can u include in an equation?
You can include state symbols in balanced symbol equations.
Some examples of state symbols?
(s) for solid, (l) for liquid, (g) for gases, and (aq) for substances disolved in water, called aqueous solutions.
What is the law of conservation of mass?
states that no atoms are lostor made during a chemical reaction,so the mass of the reactants.
What happens in some reactions where the law of conservation of mass is broken?
the rule seems to be broken because the mass appears to change.
When does the law of conservation of mass broken?
this usually when gasses are reactants or products.
What is an example of the law of conservation of mass broken?
if the product is a gas it might escape in the air.
Why is there extra mass?
the extra mass is because oxygen gas from the air is a reactant.
What is a mixture made up of?
is made up of two or more mixture that are not chemically comined together.
What are mixtures separated by?
mixtures are separated by physical processes.
What do physical processes do not involve?
does not include chemical reactions.
So no new substances are made.
What is filtration?
separates substances insoluble in a solvents from those that are soluable in the sovent.
An example of filtrantion?
sand can be seprated from salt solution using filtration
What can crystillisation be used for?
separates a soluable solid from a solvent.
what is an example of crystillisation?
sault (sodium chloride) from salt solution
What is distillation?
separates a solvent from soluable solids dissolved in the solvent.
Give an example for distillation
seawater is distilled to obtain usable water
What is fractional distillation?
fractional distillation is a way to separate mixtures of miscible liquid.
Give an example of fractional distillation
ethonal and water.
Miscible liquids dissolve in each other.
They do not form differemt layers
What do the liquids have?
Have different boiling points.
The liquid with the lowest boiling point is collected first.
What can u do to help during the seperation?
u can add a fractionating column to the distilation apparatus.
What is fractional distillation?
fractional distillation is a way to seperate ethanol from a fermented mixture in the alcoholic drinks industry.
What is a way to use paper chromatography?
is a way to separate substances from a mixture in
solution
It works becuase some compounds are more soluble than others in the solvent.
What paper chromatography?
is a way to separate food colourings
Who was the first to have ideas about the atom?
The acient Greeks
What did Dalton do?
In the early 1800s, Dalton linked his ideas to strong experimental evidence.
What did Dalton suggest?
atoms were tiny, hard sphere.
The atoms could not be divided or split?
What happened at the end of the 1800s?
Thomoson discovered a tiny negative charged particle called electrons.
What did Thomoson propose?
‘the plum puding’ model for the atom.
What did Thomos imagine the atom as?
He imagined the electrons as the bits of plum in a plum pudding.
What happened 10 yrs later?
Geiger and Marsden were experimenting with alpha particles.
What are alpha particles?
Dense positively charged particles
How did Geiger and Marsden experiment with alpha particles?
They fired alpha particles at very thin peice of gold foil.
A few alpha particles were repelled showing that there must be a tiny spot of positive charge in the centre of the atom.
What did Rutherford propose?
Rutherford proposed the nuclear model
WHat is the nuclear model?
The nuclear model is electrons orbiting around a nucleaus the nucleus contains positively charged protons.
What did Bohr do?
Bohr then revised the nuclear model.
He suggested that that the electrons were orbiting the nucleus in energy levels (or shells)
Where are the electrons set up?
the electrons were a set distance from the nucleus.
Bohr’s theoretical calculations matched the experimental observation.
What happened in 1932?
In 1932, Chadwick provided the experimental evidence that showed the existence of unchanged particles.
What Chadwick show?
the existence of neutrons
What did the centre of the atom contain?
two types of sub-atomic particles - protons and neutrons
What are electrons?
they are tiny negatively charged particles
where the electrons move around?
They move around the nucleus
Does an atom have any charge?
atoms have no overall charge
Why does the atom have no overall charge?
the number of electrons is equal to the number protons
what charge does a proton have?
+1
what charge does a electron have?
-1
what do all the atoms of an element contain?
the same number of protons
what are all the atoms of an element contain the same number of protons called?
atomic number
How are the elements in the periodic table arranged in?
arranged in orders of their atomic number
The atomic number is also the number of electrons in a atom of an element
what is the mass number?
is the total of particles in the nucleus of an atom, so it is the number of protons plus the number of neutrons.
What is an ion?
a charged atom (or a group of atoms)
What will happen if an ion gains electrons?
it becomes negative ion
Why does the ion have an overall negative charge?
this is because it has more electrons (-) than protons(+)
what is an example of a overall negatively charged ion?
an oxygen atom gains two electrons to form a negative ion.
What is the formula for the eample an oxygen atom gains two electrons to form a negative ion?
the formula of the ion is writen 0 squared
What atom looses electrons
it becomes positive ion
why when it lost electrons it becomes positive?
because it has more protons than electrons
what is an example of an atom loosing electrons?
a lithium atom loses an electron to form a positive lithium ion, Li power of +
How small is an atom?
a tenth of a billionth of a metre across (0.000 000 000 1m)
what is 0.000 000 000 1m in standard form?
1 x 10^-10
What do atoms of the same elelment have?
always have the same number of protons
They often have the same number of protons but what can be different?
the number of neutrons
What are same elements with different number of neutrons called?
isotopes
What do isotope of an element have?
different physical propporties, but always have same chemical properties
How are electrons aranged?
around the nucleus in shells
What does each shell represent?
different energy levels
What do electrons occupy?
lowest energy level (shells)
