Chemistry OCR, C4

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What does arranging the elements in order of proton number do?
gives repeating patterns in the properties of elements
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What did Dobereiner discover?
some elements with similar properties formed groups of threes, triads
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What did Newlands discover?
suggested when elements were arranged in increasing atomic weight, patterns in properties could be seen. He called this the law of octaves
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What did Mendeleev discover?
presented his periodic table which grouped similar elements together and showed repeating patterns
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How did Mendeleev use his periodic table to predict the existence of unknown elements?
he was able to work the atomic mass of the elements and so predict their properties
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What is a vertical column in the periodic table?
a group of elements with similar properties
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What is a horizontal row in the periodic table?
a period
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What are the chemical symbols for lithium, sodium and potassium?
Li, Na and K
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What happens to alkali metals when exposed to air?
alkali metals are shiny when freshly cut but tarnish rapidly in moist air due to reaction with oxygen
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What are the properties of alkali metals the further an element is down the group?
the higher the reactivity, the lower the melting and boiling points, the higher the density
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Why do alkali metals have similar properties?
they all have one electron in their outer shell and become more reactive as you go down the group because the outer shell gets further from the influence of the nucleus and the outer electron is lost more easily
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What is formed when alkali metals react with water?
an alkaline solution of a hydroxide and hydrogen, MOH (M represents alkaline metals)
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What is formed when alkali metals react vigorously with chlorine?
colourless, crystalline salts, MCL (M represents alkali metals)
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What is the equation for the reaction between potassium and water?
Potassium + Water = Potassium hydroxide + hydrogen, 2K +2H^2O + H^2
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What are safety precautions for handling hazardous chemicals?
using safety screens, using small amounts and low concentrations of the chemicals, working in a fume cupboard, no eating/drinking when working with chemicals, no using flammable substances near naked flames
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What are ways of preventing hazards when working with alkali metals?
use small amounts of the metals, wear safety glasses ans use safety screens ensure metals are stored under oil with the lids tightly secured
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What are the chemicals symbols for chlorine, bromine and iodine?
Cl, Br and I
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What are the states of chlorine, bromine and iodine at room temperature?
chlorine is a green gas, bromine is a brown liquid and iodine is a dark purple/grey solid
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What do halogens consist of?
diatomic molecules, they only exist in pairs of atoms
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What are the properties of halogens the further down the group?
the lower the reactivity, the higher the melting and boiling points and the higher the density
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Why do halogens have similar properties?
they all have seven electrons in their outer shell and become less reactive as you go down the group because the outer shell gets further from the influence of the nucleus and an electron is less easily gained
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How can a trend in reactivity of halogens be shown by their displacement reactions and by their reactions with alkali metals?
A more reactive halogen will displace a less reactive halogen from an aqueous solution of its salt and when reacting with alkali metals, form ionic compounds
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What are the safety precautions when working with halogens?
wear safety glasses, work in a fume cupboard, make sure room is well ventilated, use small amounts of dilute concentration, avoid working near naked flames
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What are the state symbols: (s), (l), (g), (aq)
solid, liquid, gas and aqueous solution
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What is the structure of an atom?
an atom has a small, central nucleus made up of protons and neutrons with electrons arranged in shells around the nucleus
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What is the relative mass and relative charge of a proton?
relative mass = 1, relative charge = +1
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What is the relative mass and relative charge of a neutron?
relative mass = 1, relative charge = 0
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What is the relative mass and relative charge of an electron?
relative mass = nearly zero, relative charge = -1
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What does the number of electrons in an atom equal?
equals the number of protons
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What do all atoms of the same element have the same number of?
protons
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How are elements in the periodic table arranged by?
arranged in order of proton number
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What do some elements (for example: lithium, sodium and potassium) emit when heated?
distinctive flame colours
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What does light emitted from the flame of an element produce?
a characteristic line spectrum
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What has the study of spectra done to help?
helped chemists to discover new elements
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How does a shell fill with electrons on the periodic table?
a shell fills with electrons across a period (row)
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What do elements in the same group have the same number of?
they have the same number of electrons in their outer shell
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How are the chemical properties of an element determined by?
by its electron arrangement
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What is evidence that molten compounds of metals with non-metals contain charged particles called ions?
they conduct electricity
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What is an ion?
an atom (or group of atoms) that has gained or lost electrons and so has an overall charge
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What are compounds of group 1 metals with group 7 elements called?
ionic compounds
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Why do solid ionic compounds form crystals?
because they're ions are arranged in a regular lattice
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What happens to the ions when an ionic crystal melts or dissolves in water?
the charged ions are able to move around independently in the liquid and so conduct electricity
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Other cards in this set

Card 2

Front

What did Dobereiner discover?

Back

some elements with similar properties formed groups of threes, triads

Card 3

Front

What did Newlands discover?

Back

Preview of the front of card 3

Card 4

Front

What did Mendeleev discover?

Back

Preview of the front of card 4

Card 5

Front

How did Mendeleev use his periodic table to predict the existence of unknown elements?

Back

Preview of the front of card 5
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