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45 Cards in this Set
- Front
- Back
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What is nanotechnology? |
The use of technology that manipulates and investigate the properties of materials on nanoscale |
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Nanoscale |
Objects between 1-100nm |
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Steps to convert |
1. Convert to metres 2. Convert to scientific notation 3. X by 10^-9 |
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Uses of nanotech |
Drug delivery: nanoworms, too small for the immune system to attack them Fabrics: waterproof properties |
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What is the bottom up and top down methods? |
Bottom up: uses atoms to gradually build up the nano particles
Top down: breaks down a bulk material to form the nano particle |
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3 ways nanoparticle size is good: |
1. Absorption of molecules - removes unwanted chemicals 2. Transportation of molecules 3. Catalysts - SA can be used to increase the rate of chemical reaction. It's small enough that it isn't used up in the reaction but can speed it up |
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When and what did john dalton propose |
1802, the atomic theory of matter. All matter is made up of tiny spherical particles which are indivisible and indestructible |
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Define elements |
Elements contain one type of atom |
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Define compound |
Different types of atoms in fixed ratios. Can be broken down into individual elements |
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What can carbon form |
Giant molecules and lattices. Eg) diamond and graphite |
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Define monatomic |
Exists only as a single atom. Noble gases |
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How is the symbol of elements set out |
A - mass no X - element symbol Z - atomic no |
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Nucleons |
Protons and neautrons found in the nucleus |
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Electron weight compared protons |
1/1800 |
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Isotopes |
Same number of protons, different number of neutrons |
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Isotopes have the same what? |
the same chemical properties, but different physical properties as their original element |
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Electromagnetic radiation |
The light given off when electrons are excited |
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Emission spectra |
Coloured lines that appear on black paper when the light from an excited atom is put through a prism |
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Violet light has what energy level? |
High energy |
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What information is gathered from the emission spectra? |
1. Atoms of the same element produce the same lines on the spectra 2. Each atom has a unique line spectra, therefore a unique electronic structure |
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What did Bohr propose? |
1. Electrons revolve around the nucleus 2. Electrons orbit in corresponding energy levels 3. Electrons only occupy fixed energy levels, they can't float between 4. Orbits of a larger radii = higher energy levels |
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When was the Bohr model developed and what did it entail |
1913. Neil Bohr developed a new model of a hydrogen atom that described the emission spectra |
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Electron shells are |
Different energy levels of an atom |
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Define ground state and excited state |
Ground state: the lowest energy level of an atom Excited state: when an electron absorbs energy and jumps to a higher energy kevel |
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Define electron configurstion |
The arrangement of electrons around the nucleus |
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Ionisation emergy |
The energy needed to remove an electron from an atom |
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Define electron configurstion |
The arrangement of electrons around the nucleus |
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Formula for the number of electrons a shell can homd |
2n^2 |
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Define valence electron |
The electrons found on the outer most shell of an atom. It is involved in chemical reactions |
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What can't the Bohr model explain? |
1. Can't accurately predict emission spectra of atom with more than one electron 2. Unable to explain why shells only hold 2n^2 3. Why the fourth shell takes 2 electrons before the 3rd shell can fill |
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What did schrodinger propose and when |
1926, proposed that electrons behave in waves around the nucleus. Developed model of atom called quantum mechanics |
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Difference between the Bohr and schrodinger model |
Bohr viewed electrons as hard particles that revolve in orbits. Schrodinger viewed them as wave like properties. They occupy a 3D space around the nucleus called an orbital |
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What are the subshells |
S, p, d and f. S holds 2, p holds 6, d holds 10 and f holds 14 |
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Who created one of the first periodic tsbles |
Mendeleev |
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What are the main group elements |
1-2, 13-18 |
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What do groups 3-12 hold |
Transition metals |
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What do the blocks of subshells tell us |
The blocks of subshells tell us which subshells has the highest energy for that atom |
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What do periods of a PT signify |
The period is how many electron shells there are. Runs horizontal |
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What is core charge/how is it calculated. What is it's trend on the PT |
Core charge is the measure of attraction between valence electrons and the nucleus. Core charge = number of protons - inner electrons. Increases left to right, remains constant down a group |
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Electronegativity trend/definition |
Electronegativity is the ability of an atom to attract electrons towards itself. Increases across a period as the core charge does, decreases down a period as shells are added. Greater core charge = greater electronegativity |
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Atomic radius trend/definition |
Decreases left to right. Increases down a group. The measurement for the size of an atom |
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First ionisation energy |
The amount of energy required to remove an electron from an atom. Increases across a period, decreases down a period |
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Metallic character |
Decreases left to right. Increases down a group |
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Reactivity trend/definition |
How easily an atom loses or gains an electron. For metals: increases down a group. For non-metals: increases across a period, decreases down a group |
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Timeline of atom development |
1804: dalton- atoms 1897: Thomson - electrons 1911: Rutherford - nuclear atom 1913: Bohr - shell model 1926: schrodinger - quantum mechanics 1932: Chadwick- neutrons |
