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chemistry > chemical patterns > Flashcards

chemical patterns Flashcards

1
Q

whats the equation for the reaction between sodium and chlorine?

A

sodium + chlorine —> sodium chloride

2Na + Cl2 —> 2NaCl

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2
Q

how does sodium react with chloride?

A

vigorously, to give a yellow flame

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3
Q

whats the equation for the reaction of group 1 elements with water?

A

metal + water —> metal hydroxide + hydrogen

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4
Q

what are group 1 metals?

A

flammable, hydroxides harmful and corrosive

should be kept away from water and naked flames

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5
Q

when working with halogens, what should you do?

A
  • safety glasses
  • avoid working near naked flames
  • watch teacher demonstrations carefuly
  • make sure room is well ventilated
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6
Q

what are common safety precautions for handling hazardous substances?

A
  • safety screens
  • wearing gloves
  • eye protection
  • washing hands after handling chemicals
  • working in fume cupboard
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7
Q

what is a group?

A

vertical column of elements that have similar properties

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8
Q

what do group 1 elements include?

A
  • lithium
  • potassium
  • sodium
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9
Q

what is the relationship between the group # and # of electrons?

A

group # corresponds to # of electrons in outer shell of atom

group 1 elements have 1 electron in outer shell
group 7 elements have 7 electrons in outer shell

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10
Q

what is a period?

A

horizontal row of elements

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11
Q

what are examples of elements in the same period?

A
  • lithium
  • neon
  • carbon
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12
Q

what are the steps to write a balanced equation?

A

1) write word equation
2) substitute formulae for names of elements/compounds involved
3) balance equation by adding # in front of reactants/products
4) write balanced symbol equation

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13
Q

what is the name of group 1?

A

alkali metals

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14
Q

what happens if you go further an element down the group?

A
  • higher reactivity
  • lower melting and boiling points
  • higher density
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15
Q

what is the trend in group 1 metals?

A

have 1 electron in outer shell

more reactive down group

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16
Q

what should you do when working with group 1 metals?

A
  • use small amounts of metals
  • safety glasses
  • watch teacher demonstrations carefully
  • ensure metals stored under oil
  • avoid working near naked flames
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17
Q

what do alkalis react to form?

A

compounds

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18
Q

what do alkali metals look like?

A

shiny when freshly cut, but tarnish in moist air, go dull and become covered in metal oxide

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19
Q

how do alkali metals react with chlorine?

A

vigorously to form white crystalline salts

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20
Q

whats the general equation where M refers to the alkali metal?

A

2M + Cl2 —> 2MCl

eg

lithium + chlorine —> lithium chloride
2Li + Cl2 —> 2LiCl

21
Q

what do alkali metals react with water to form?

A

metal hydroxide and hydrogen gas, mh dissolves in water to form alkaline solution:
2M + 2H20 —> 2MOH + H20

eg:
potassium + water —> potassium hydroxide + hydrogen
2K + 2H20 —> 2KOH + H2

22
Q

what are examples of reactivity of alkali metals increasing further down a group?

A
  • lithium, reacts quickly, water
  • sodium, reacts vigorously, water + melts
  • potassium, reacts vigorously, water that sparks produce
23
Q

what is the names of group 7?

A

halogens

24
Q

what can you use halogens for?

A
  • bleach dyes

- kill bacteria in water

25
Q

at room temp and pressure, what happens?

A 
chlorine = green gas
bromine = brown liquid
iodine = dark purple solid
26
Q

what do all halogens consist of?

A

diatomic molecules

only exist in pairs of atoms

27
Q

halogens react with alkali metals to produce water?

give an example

A

halides

lithium + chloride —> lithium chloride
2Li + Cl2 —> 2LCl

28
Q

what is the trend in group 7?

A

7 electrons in outer shell

less reactive going down group

29
Q

what should you do when working with halogens?

A
  • safety glasses
  • work in fume cupboard
  • use small amounts of dilute conc
  • room = ventilated
30
Q

what are ions?

A

atoms that’ve gained/lost electrons

as # of protons + electrons not equal, ions have overall charge

31
Q

what is ionic bonding?

A

occurs between metal + non metal

32
Q

electrons transfer from 1 atom to another to form electrically charged ions how?

A
  • atoms that lose electrons become positively charged ions

- atoms that gain electrons become negatively charged ions

33
Q

compounds of group 1 and 7 elements are what?

A

ionic compounds (salts).

  • IC form crystals bc irons arranged into regular lattice
34
Q

what happens to ionic crystals when they melt/dissolve in water?

A

they conduct electricity –> bc charged ions are free to move around

35
Q

what is inside an atom?

A

has nucleus made up of protons and neutrons surrounded by electrons in shells

36
Q

what do all protons and atoms have?

A

atom:

  • same # of protons as electrons so atom is neutral
  • atoms of same element have same # of protons

proton:
- same mass as neutron, mass of an electron is negligible

37
Q

what does the electron configuration of an atom show?

A

how electrons are arranged in shells around the nucleus

38
Q

what is spectroscopy?

A

when elements are heated, they emit distinctive coloured flames

light emitted produced line spectrum

each element, own spectrum

study of spectra used to analyse unknown substances + discover new elements eg helium —> first seen in light from sun

39
Q

what are the colours of elements when heated?

A

sodium - yellow
potassium - lilac
lithium - red

40
Q

how do you write a balanced equation?

A

follow these steps…

1) write word equation
2) substitute formulae
3) balance by adding #
4) write balanced equation

41
Q

how do halogens react with other elements?

A

form compounds

reaction with alkali metals highly exothermic forming ionic compounds

eg:
lithium + bromine —> lithium bromide
2Li + Br2 —> 2LiBr

42
Q

what is the displacement reactions of halogens?

A

reactive halogen displace less reactive halogen from an aqueous solution of its salt meaning chlorine will displace both bromine and iodine, while bromine will displace iodine

eg:
potassium iodide + chlorine —> potassium chloride + iodine

2Kl + Cl2 —> 2KCl + l2

43
Q

what are the properties of compounds of halogens with alkali metals?

A

compounds of alkali metals and halogens conduct electricity when molten or dissolved in water

made up of ions

44
Q

what are ionic compounds?

A

electrically neutral substances that have positive and negative charge

45
Q

what is the history of the periodic table?

A

Dobereiner said some elements with similar properties formed groups of 3 - triads eg lithium, sodium and potassium

Newlands said when elements were arranged in order of increasing atomic weight, some repeating patterns in properties could be seen - law of octaves

Mendeleevs table allowed similar elements to be grouped together and show repeating patterns
- left gaps in table for non discoveries

46
Q

what is the table of atom particle?

A

atom particle relative mass relative charge
p 1 +1
n 1 0
e nearly 0 -1

47
Q

what are elements?

A

made of only 1 kind of atom, all atoms of an elements have same number of protons

diff elements have diff proton numbers and arranged in a order of increasing proton number in the pt giving repeating patterns in properties of elements

48
Q

what happens when lithium, potassium and sodium react with cold water?

A
  • float due to low density

- produce bubbles of hydrogen gas

chemistry (7 decks)

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