Science

1.5.25

Classifying Matter 

Key Terms

Atom - Smallest particle of matter

Element - Pure substance made from only one atom type

Compound - Pure substance made from two or more different elements. Chemically bonded and chemically broken up

Mixture - Two or more pure substances that aren’t chemically bonded.

Pure substance - Sample of matter with definite chemical and physical properties.

Lattice - Substance made from two or more chemically combined atoms. Includes at least one metal.

Molecule - Substance made from two or more chemically combined atoms. Must all be non metals, and discreet - individual units with nothing around.


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Atomic Structure

Structure of an Atom

Protons - Positive, found in nucleus and heaviest part of atom

Neutrons - Neutral and holds protons together in nucleus

Electrons - Negative charge, smallest particle and in constant motion. Can be shared or moved between atoms.

Types of Element

Types of atom that makes up each element are determined by the number of protons.

Atomic Number - Number of protons in nucleus

Mass Number - Total number of protons and neutrons in nucleus

Atoms are electrically neutral when number of electrons = number of protons 

8.5.25

Electron Configuration

Bohr Model 

Electrons grouped in different electron levels called Electron Shells.

Each shell has a maximum number of electrons with lower shells filling first.

Max shells = 2n*2



9.5.25

Periodic Table 

Order - Determined by atomic number

Group - Determined by how many in outer shell with all elements within the group having the same amount.

Period - How many shells there are


Metals and Non - Metals

Physical Properties

Metals 

  • Lustrous

  • Good conductors

  • High melting point

  • Malleable 

  • Ductile (drawn into wires)

  • Solid at room temperature

  • Opaque when thin sheet

  • Sonorous

Non - Metals

  • Dull

  • Poor conductors

  • Any state of matter at room temperature

Metalloids have properties of metals and non - metals

Groups

Group 1 - Alkali Metals 

  • Non acidic

  • Valence electron of 1

  • Quite reactive with water

  • Soft, shiny and silvery

  • Hydrogen is not alkali

Group 2 - Alkaline earth metals

  • Naturally found in earth

  • Less reactive than alkali metals

Group 3 - 12 - Transition metals

  • Form ions and compounds

  • Hard and high density with high melting point

Group 17 - Halogens

  • Reactive non -metals

  • React with metals to form ionic compounds

  • Varying states at room temperature

Group 18 - Noble gases

  • Unreactive because of stable valence shells

  • Gas at room temperature

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Ions

Formed by the addition or removal of electrons from neutral to achieve stability


Key Terms

Ions -  Positively or negatively charged atom or group of atoms

Cations - Positively charge ion - Loses electrons

Anions - Negatively charged ions - Gains electrons


23.5.25

Electron Transfer & Ionic Bonding

Ionic Compounds

Ionic compounds form when a metal and a non metal react. 

Ionic compound = Metallic cation + non-metallic anion

There is a transfer of electrons, with oppositely charged ions joining and forming a lattice.


Electron Transfer Diagrams

Show the path electrons take when move from the metal and added to non metal during ionic bonding.


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Ionic Compound

Rules 

  • Name Cations (metals) then anions

  • For transition metals indicate valency through numerals after the name in brackets. E.g Fe(III)

  • Cations name remains the same (Sodium), metal anions change the suffix with -ide (Chlorine = chloride)


Chemical Formula Rules

  • Write positively charged first 

  • Subscripts indicate number of ions in formula

  • Do not include charges in formula

  • If one ion do not include in transcript

Ionic Compounds Thinking Routine

  1. Write symbol and charge

  2. Calculate lowest common multiple

  3. Calculate how many cations and anions needed to equal lowest common multiple

  4. Write cation first and use chemical formula rule


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Properties of Ionic Compounds

 

Electrostatic Attraction - Attraction between oppositely charged ions


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Properties Of Ionic Compounds 2.

Solid at room temperatures

  • Ionic compounds that are solid at room temperature are called salts. 

  • They have a strong electrostatic force. 

  • Due to being a solid at room temperature, the melting point is high

  • Larger amounts of energy is needed to break apart the bonds


Why are they brittle?

Brittle when force is applied, due to the ions lining up with those that have like attractions.

  •  Like a lego wall built by a child. Stacked directly on top, leading to being unstable

Solubility

  • Water breaks apart ionic compounds as Hydrogen and Oxygen are positive and negative respectively, which attract the opposite charge of the compounds.

  • How water dissolves ions

Conductivity

  • Ions in water move to conduct electricity, because the particles are free moving.

  • Molten ionic compounds can conduct electricity, due to the particles being free moving, with thermal energy loosening bonds. 

6.6.25

Metallic Bonding

Metals occur as lattice because metallic atoms lose outer shell electrons easily, causing the metals to become cations, forming lattices and allowing electrons to float between. 


Ionic V Metallic

Ionic are metal and non metal (left and right on periodic table), with metallic being metal and metal (left and left).


10.6.25

Metallic Properties


Metallic Bond

Cations in a sea of delocalised anions

Metallic Properties

  • Lustrous 

  • Conductive

  • Malleable

  • High Melting point


Conductivity 

  • Needs to have free moving particles

  • When electric field is applied, one sides positive with electrons moving in that direction

Melting Point

  • Large amount of energy is required to overcome electrostatic attraction

  • High temperatures is needed for changes to occur


Lustrous

  • Free moving electrons reflect the light