S1-L1 Elements, Compounds & Mixtures Flashcards
What is “matter”?
- Anything that has mass
- all objects made of matter
- single chemical substance/complex mix of substances
Outline the states of matter
-Solid/ liquid/ Gas
State the processes taking place when changing from a solid to liquid to gas and vice versa as well as solid to gas and gas to solid
- melting–>vaporisation
- condensation–>freezing
- solid to gas–> sublimation
- gas to solid–> deposition
What physical changes take place when changing from steam-water-ice and vice versa
- condensing/liquefying–>freezing/solidifying
- evaporating/boiling–> melting/fusing
Define the following properties of matter:
1-Electrical conductivity 2-Heat conductivity 3-Desnity 4-M. Point 5-B. Point 6-Refractive Index 7-Malleability 8-Ductility
1-Ability to transmit electricity-like copper use in electrical wiring
2-Ability to transfer heat energy-like aluminium saucepan
3-mas:volume ratio like lead weights
4-temp when solid turns to liquid-like 0 degrees for water
5-temp when liquid becomes gas-like 100 degrees for water
6-way light passes through material bent-like 1.33 for H2O
7-ability to be shaped via hammering-like gold jewellery
8-ability to shape via puling in to wire-like tantalum-dentist instrument
Define the property “intensive” and outline example(s)
- Not dependent on amount of matter present
- could use to identify substance
- like density/ colour/ b. point
What are “extensive” properties and give some example(s)?
- Dependent on amount of matter present
- like mass/volume/weight
Describe what “physical” properties are and how they arise
- Observed by examining pure substance
- arise from molecular structure & intermolecular force’s strength
What are “chemical” properties and how do they arise?
- Observed during chemical reaction
- Arise from e- distribution around atom’s nucleus–> particularly outer (valence) e-‘s
Outline and describe “pure” substances
- Fixed set of physical + chemical properties
- can’t separate via physical processes
- properties not vary
- can only change via chemical reaction
Briefly explain what a “mixture” is
- 2 or more substances physical blend
- variable composition
- different properties for different compositions
- can separate mixture in to separate components via physical process
Define an “element”
- simplest form of matter which has unique properties
- can’t split substance in to two/ more simpler substance via chemical method
- ->like H or O
What is a “compound” and give an example?
- compounds contains two/ more chemically bonded elements in fixed proportion
- like H2O
What are “molecules” and describe them?
- most matter made up of molecules/mixture of them
- group of 2+ atoms joined together
- element can exist as atoms/molecules but compounds made of molecules
Outline a summary of Dalton’s atomic theory
- Elements combined in fixed ratios
- all matter composed of atoms
- different elements have different atoms types
- ->can characterise by atomic weight/ all same elements identical
- can create/destroy atoms
- compounds composed of 2+ atoms chemically combined in fixed proportions
- ->like H2O ratio: 2H + 1 O
- chemical reactions rearrange atoms–>changing chemical combination so identity of atom changes.
Briefly explain the following properties of atoms:
1) Mass
2) Combining power
1) -Almost all atom’s mass contained in nucleus
- protons/ neutrons/ electrons
2) -ability to form chemical bonds
- also termed valency
Structure of atom:
1) Describe the structure of the atom including the nucleus
1) -Proton (+) charged
- neutron uncharged
- nucleus surrounded by e-‘s (-) charged
- e-‘s in outermost orbital determine atom’s chemical and electrical properties
Define the “nucleons” of an atom
-Is the n. of protons and neutrons in the nucleus which is the atom’s mass number
Describe the meaning of “combining power”-valency
- Ability of atom to combine with other atoms controlled by n. of e-‘s
- ->which atom will give/take/share to form chemical compound
- relates to n. of e-‘s AND electron’s spaces in atom’s electron shells
What are “chemical symbols”?
- abbreviation/short-hand form of chemical element used in formulae
- consists of capital letter and sometimes followed by small letter
- examples: H/ O/ He (Helium)
Where are chemical names/symbols derived from and give some examples?
- From their Greek/ latin names
- examples:
- Chlorine-Greek for yellowish green; Cl
- Helium- Greek for sun; He
- Calcium-Latin for lime; Ca
- Carbon-Latin for charcoal; C
- Iron- Anglo-Saxon; Fe (Latin)
Define and describe “Relative Atomic Mass (Ar)”
- Defined as mass of one atom of element divided by mass of 1/12 of atom of C-12
- Ar of chemical element gives atom’s weight which is force makes when gravity pulls on it
- written as subscript before atom’s symbol like 1^H
Describe what “molecules” are
- Unit of 2+ atoms held together by chemical bonds
- contains atoms in defined proportions like water
- -> 2 H and 1 O
What is “molecular formulae”?
- Show n. of atoms found in 1 molecule of substance
- ->like sugar: glucose contains 6C’s/ 12 H’s and 6 O’s
- ->written as C6H12O6
