1.1- 1.5 Models of particulate nature of matter

What is an element?

Element is a substance made of atoms all containing the same number of protons and cannot be split into anything simpler

What is a compound?

Compound consists of atoms of different elements chemically bonded together in a fixed ratio

What is a mixture?

Mixture contains more than one element or compound in no fixed ratio, which are not chemically bonded

Explain the difference between compound and mixture

Compound consists of two or more elements that are chemically combined, while a mixture consists of two or more substances that are not chemically combined

Explain the difference between element and compound

Element consists of only one element, while a compound consists of two or more elements that are chemically combined

Define homogeneous mixture

Mixture with uniform composition and properties throughout

Define heterogeneous mixture

Mixture with no uniform composition and different properties throughout

Explain the simple distillation process

Simple distillation is used to separate a liquid from the solution by boiling the solution and condensing the vapour

What does simple distillation separate?

1. Liquid and soluble solid from a solution (np. wodę z roztworu z solą)

2. Pure liquid from a mixture of liquids

Explain the fractional distillation process

Technique used to separate two or more liquids that have different boiling points from a mixture (np. alkohol i woda)

Describe chromatography technique

It is used to separate solution with more than one type of solid dissolved (np. tusz)

Describe filtration

It separates undissolved solid from a mixture of solid and liquid (np. woda z piaskiem)

Define residue and filtrate

Residue is the solid left behind on the filter paper, filtrate is the liquid that passes through the filter

Describe crystallisation

It is used to separate dissolved solid from a solution

Describe recrystallisation and state what is important in this process

It is used to purify impure solids. It is important that the solid is more soluble in hot solvent than in cold.

Describe paper chromatography

It is used to separate substances that have different solubilities in a given solvent, such as identifying the components of a mixture (np. substancje z kolorowego tuszu do drukarki)

State the difference between evaporation and boiling

Evaporation is when a liquid changes into a gas. Evaporation occurs over a range of temperatures below the boiling point of a liquid. Boiling is when a liquid changes into a gas at a constant temperature.

What happens to particles during melting in terms of energy?

Particles absorb thermal energy which is converted into kinetic energy, allowing them to move more freely.

What is the main difference in particle movement between solids, liquids and gases?

In solids, particles vibrate in position but cannot change location. In liquids, particles move and slide past each other. In gases, particles move freely, quickly and randomly in all directions.

Define absolute zero

Absolute zero is the lowest possible temperature, equal to 0 K or -273.15 °C, at which atoms and molecules have zero kinetic and potential energy

Do all particles of different substances have the same velocity at the same temperature?

Particles of different substances at the same temperature have the same average kinetic energy, but may have different velocities due to different masses

What is the relationship between temperature and kinetic energy during melting?

During melting, temperature remains constant while energy is used to break bonds between particles, with no increase in kinetic energy.

What happens to particle movement as temperature increases?

As temperature increases, particle movement increases, resulting in higher average kinetic energy

Define atomic number

Number of protons

What is an isotope?

Atom of the same element containing the same number of protons but different numbers of neutrons. They have the same chemical properties, but different physical properties such as density (electrical conductivity stays the same as exception)

In terms of isotope, what is abundance?

Abundance is the amount of each isotope present in a sample of an element.

What is mass spectra used for?

Mass spectra is used to determine the relative atomic mass of an element from its isotopes.

What is the electromagnetic spectrum?

The electromagnetic spectrum is a range of frequencies that covers all electromagnetic radiation and their respective wavelengths and energy.

What is frequency in terms of electromagnetic spectrum?

Number of waves per second

What is the difference between a continuous and line spectrum?

A continuous spectrum is a spectrum that contains all frequencies of light whereas a line spectrum is a spectrum that only shows certain fixed frequencies of light.

What happens when electrons return to their original energy levels after being excited?

When electrons return to their original energy levels, they emit energy.

What region of the electromagnetic spectrum do electron jumps from n∞ to n1correspond to?

Electron jumps from n∞ to n1 correspond to the ultraviolet region of the spectrum.

What region of the electromagnetic spectrum do electron jumps from n∞ to n2 correspond to?

Electron jumps from n∞ to n2 correspond to the visible region of the spectrum.

What region of the electromagnetic spectrum do electron jumps from n∞ to n3 correspond to?

Electron jumps from n∞ to n3 correspond to the infrared region of the spectrum.

Define convergence in relation to emission spectra.

Convergence is when the spectral lines get closer together towards the higher energy end of the spectrum.

Describe the emission spectrum of hydrogen

The emission spectrum of hydrogen in the visible region shows lines converge at a higher frequency.

What does the line emission spectrum of the hydrogen atom provide evidence for?

The line emission spectrum of the hydrogen atom provides evidence for the existence of electrons in discrete energy levels which converge at higher energies.

Define the term ionisation energy, in the context of emission spectra.

Ionisation energy is the maximum amount of energy an electron can reach, corresponding to the energy required for the electron to escape the atom.

Why does ionisation energy increase for electron even in the same subshell?

• more electrons removed

• stronger pulle of nucleus on remaining electrons due too ↑ efefctive nucleur charge

The 4s subshell fills first and empties before the 3d subshell.

.

Down a group ionisation energy decreases as shielding effect increases, therefore, the attraction of outer electrons to the nucleus decreases.

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Why does ionisation energy increase across a period?

Ionisation energy increase across a period because the nuclear charge increases and the shielding by inner shell electrons remains the same.

Why do the successive ionisation energies of an element increase?

Successive ionisation energies increase because removing electrons from a positive ion becomes more difficult due to increasing attractive forces and decreasing shielding.

What is the evidence to confirm that mixture is heterogeneous?

More than one type of material is visible

Jaki jest wzór na odczytanie relative molecular mass z mass spectrum gdy ma się intensity i masy izotopów?

(isotope 1 x intensity 1) + (isotope 2 x intensity 2) : (sum of intensities)

Which light has the greatest energy>

Ultraviolet

Explain why the first ionisation energy is higher for nitrogen than for oxygen

The 2p sublevel for nitrogen is not completely full and there are no paired electrons on this sub level. In contrast oxygen has 2 paired electrons that are paired on the 2p sub level. Since there are repulsions between paired electrons, lower energy is needed to remove first valence electron than in the case of unpaired electrons.

When do coloured solutions form?

When electrons can absorb certain wavelengths of visible light between energy levels in partially filled split d orbitals.

Does Cu follow the usual rules of electron configuration?

No because it has 3d sub level completely filled before 4s

What is orbital?

Location where there is a high probability of finding an electron

Explain ionisation energy

The amount of energy required to remove the one mole of electrons from one mole of gaseous atoms

Zapełniona cała powłoka niesparowanymi jest more stable niż zapełnienie np jedną parą. Więc ten pierwszy pierwiastek będzie mieć większą 1st ionisation energy

Why Argon has such a high first ionisation energy?

It has complete octet in the third energy level which makes it very difficult to lose an electron

What is electronegativity?

The attraction the atom of an element has for the shared pair of electrons in a covalent bond. This attraction will increase when there are fewer energy levels.

What assumptions are made in the kinetic theory of gases?

The assumptions made in the kinetic theory of gases are:

The gas molecules are moving very fast and randomly

The molecules hardly have any volume

The gas molecules do not attract or repel each other (nointermolecular forces)

No kinetic energy is lost when the gas molecules collide with each other (elastic collisions)

The temperature of the gas is directly proportional to the average kinetic energy of the molecules

Define elastic collision.

An elastic collision is when no kinetic energy is lost when gas molecules collide with each other.

What is an ideal gas?

An ideal gas is a gas that follows the kinetic theory of gases.

What factors does the volume of a gas depend on?

The volume that a gas occupies depends on its pressure and temperature.

State Boyle's Law.

Boyle's Law states that pressure is inversely proportional to volume at constant temperature.

Define Charles' Law.

Charles' Law states that volume is directly proportional to temperature in Kelvin at constant pressure.

Podaj jednostki w równaniu pv = nRT

p w Pa, V w m3, n w molach, R w J/Kxmol, T w Kelvinach

Under what conditions do real gases show significant deviation from the ideal gas equation?

When the temperature is very low or the pressure is very high, because the volume of gas molecules becomes significant compared to the total volume.

What happens to the fraction of space occupied by gas molecules at low temperatures and high pressures?

At low temperatures and high pressures, the fraction of space taken up by the molecules becomes substantial compared to the total volume.