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Flashcards in Elements Of Life Deck (103)
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1

[EL1] What is the atomic number?

The number of protons present in the nucleus of an atom.

2

[EL1] What is the mass number?

The total number of nucleons (protons and neutrons_ present in the nucleus of an atom.

3

[EL1] What is the relative atomic mass?

The mean mass of an atom of an element compared to 1/12th the mass of an atom of carbon-12.

4

[EL1] What is the relative molecular mass?

The mean mass of a molecule compared to 1/12th the mass of an atom of carbon-12.

5

[EL1] What is relative formula mass?

The sum of the mean masses of all atoms in the formula of a compound compared to 1/12th the mass of an atom of carbon-12.

6

[EL1] What is the relative isotopic mass?

The mass of an atom isotope compared with 1/12th the mass of an atom of carbon-12.

7

[EL1] What is the mole?

The amount of substance containing as many particles as there are atoms in 12g of carbon-12.

1 mole = 6.02 x 10²³ items (Avagadro constant).

8

[EL1] What is an ionic equation?

An equation in which only the non-spectating ions are shown.

9

[EL1] How is percentage yield calculated?

%yield = ( actual yield / expected yield ) x 100

10

[EL1] How is percentage composition by mass calculated?

%composition = ( mass of desired substance / mass of mixture ) x 100

11

[EL1] How is a standard solution prepared from a concentrated solution?

- A certain volume of the concentrated solution is added to a volumetric flask in order to get the desired final volume.

- Distilled water is added to the volumetric flask up to the line on its neck.

12

[EL2] What are the shapes of s and p orbitals?

s: Sphericle

p: Like two balloons attached at the knot (repeated in x, y and z-axis)

https://cdn.britannica.com/54/3254-050-6DB9F924/Electron-orbitals-orbital-atoms-p.jpg

13

[EL2] What are orbitals?

- Regions in the space around an atom where electrons are most likely to be found.

- They can contain a maximum of two electrons.

14

[EL2] How are electrons arranged in orbitals?

- Electrons fill from the lowest energy orbital first.

(e.g. they will not fill the fourth shell first)

- Electrons will prefer (not as if they have a conscience to prefer but...) to occupy orbitals by themselves, and will only pair with other electrons if no other lower energy orbitals are available to fill.

15

[EL2] How are orbital filled on the energy level diagram?

Each box on the diagram represents one orbital and each arrow represents one electron.

The electrons spin at the same rate in either a clockwise (↑) or anticlockwise (↓) direction.

Electrons fill each of the 2p orbitals individually before pairing.

https://drive.google.com/file/d/1aB-kEytdxc_uPbMw8iMBgqyesorK63dI/view?usp=sharing

16

[EL2] Why does the 4s orbital fill before the 3d orbital?

The 4s orbital is of lower energy than the 3d orbital so it fills up first.

17

[EL2] What is the plum pudding model?

Charge is equally distributed around the atom.

18

[EL2] What did the Geiger-Marsden experiment show?

That the atom contained a very small, dense. positive nucleus.

19

[EL2] What is fusion?

When two lighter nuclei collide and combine to form a heavier nucleus, releasing energy.

20

[EL2] What are the conditions for fusion to happen?

A very high temperature and pressure.

21

[EL3] What is covalent bonding?

- When a pair of electrons is shared between two atoms.

- Covalent bonds are strong as there is a strong electrostatic attraction between these share electrons and the nuclei of the bonded atoms.

22

[EL3] Why do giant covalent lattices have a much grater melting point than simple covalent molecules?

The covalent bonds between the atoms in a giant covalent lattice are much stronger than the induced di-di interactions between the simple covalent molecule.

23

[EL3] Why are ionic substances only conductive when dissolved?

- When ions are in a solid, they are unable to move so they cannot carry a charge.

- Dissolving the solid causes the ions to be mobile so they are free to carry charge.

24

[EL3] Why do covalent and ionic lattices have high melting points?

Both lattices contain atoms that have multiple strong bonds around them, these bonds take a lot of (thermal) energy to break.

25

[EL3] What are the non-linear bond angle conditions?

104.5⁰

Two bonded pairs.

Two lone pairs.

26

[EL3] What are the trigonal planar bond angle and conditions?

120⁰

Three bond pairs.

27

[EL3] What are the trigonal pyramidal bond angle and conditions?

107⁰

Three bonded pairs.

One lone pair.

28

[EL3] What are the tetrahedral bond angle and conditions?

109.5⁰

Four bonded pairs.

29

[EL3] What are the octahedral bond angle and conditions?

90⁰

Six bonded pairs.

30

[EL3] How do different numbers of bonded and lone pairs produce different shapes in molecules?

Lone pairs repel more than bonded pairs.