2 Atoms, elements and compounds Flashcards

1
Q

elements

A

simplest structure that cannot be broken down into smaller parts or changed into another substance.

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2
Q

Compound

A

a substance made from two or more different elements that have been chemically joined

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3
Q

mixture

A

a combination of two or more substances (elements or compounds) that are not chemically combined

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4
Q

atom structure

A

a central nucleus containing neutrons and protons surounded by electrons in shells

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5
Q

relative charges of proton, neutron and an electron

A

Electron is -1
Proton is +1
neutron is 0

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6
Q

relative masses of proton, neutron and an electron

A

Electron is 1/1835
Proton is 1
Neutron is 1

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7
Q

proton/atomic number

A

number of protons in the nucleus of an atom

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8
Q

mass/nucleon number

A

the total number of protons and neutrons in the nucleus of an atom

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9
Q

isotopes

A

different atoms of the same element that have the same number of protons by different numbers of neutrons

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10
Q

chemical properties of isotopes

A

isotopes of the same element have same chemical properties because they have the same number of electrons and therefore the same electronic configuration

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11
Q

relative atomic mass formula

A

(abundance x mass number)/100

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12
Q

cations

A

positive ions

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13
Q

anions

A

negative ions

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14
Q

ionic bond

A

a strong electrostatic attraction between oppositely charged ions

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15
Q

ionic compounds properties

A

high melting and boiling points
good electrical conductivity when aqueous or molten and poor when solid

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16
Q

giant lattice structure of ionic compound

A

regular arrangement of alternating positive and negative ions

17
Q

why do ionic compounds have high melting points?

A

have strong electrostatic forces of attraction between oppositely charged ions. Large amounts of energy are needed to break the many strong bonds.

18
Q

why are ionic compounds a good conductor of electricty when liquid?

A

Because their ions are free to move from place to place

19
Q

How are covalent bonds formed

A

when a pair of electrons is shared between two atoms leading to a full shell

20
Q

why do simple molecular bonds have low melting and boiling points

A

The have weak intermolecular forces between molecules, low energy is required to break them

21
Q

why do simple molecular structures have poor electrical conductivity

A

no free ions that can move

22
Q

diamond

A

each carbon atom is covalently bonded to 4 other carbon atoms
- tetrahedral
- high m.p and b.p
- no conduction of electricity

23
Q

graphite

A

each carbon atom is covalently bonded with 3 other carbon atoms, resulting in a delocalised electron
- flat sheets
- high m.p and b.p
- can conduct electricity

24
Q

diamond usage

A

cutting tools, jewelery

25
Q

graphite usage

A

pencils, lubricants, electrodes

26
Q

structure of silicon (IV) oxide

A

tetrahedral macromolecular structure similar to diamond
- each Silicon atom is covalently bonded with 4 oxygen atoms
- high m.p and b.p
- rigid and hard
- non conductor of electricity

27
Q

similarities of diamond and silicon oxide

A
  • hard, rigid, 3D structures
  • tetrahedral crystals
  • non-conductors of electricity
  • high m.p and b.p
28
Q

why does silicon oxide have a high melting point

A

SiO is a macromolecular structure that consists of an extensive network of strong covalent bonds. A large amount of energy is needed to break some of these bonds in order to melt it, hence high melting point

29
Q

metallic bonding

A

electrostatic attraction between the positive ions in a metallic lattic and a sea of delocalised electron