Chemistry atomic structure and periodic table from pmt past paper

1.1 simple atomic model

What type of substance is Substance A if it contains only one type of atom and does not conduct electricity?

Non-metallic element.

What type of substance is Substance B if it contains two types of atoms that are chemically combined in fixed proportions?

Compound.

What is the name of the elements in Group 0 of the periodic table?

Noble gases.

Which statement about the elements in Group 0 is correct?

The boiling points increase down the group.

What type of particles are found in a sample of neon, which is in Group 0?

Atoms.

What is the empirical formula of an oxide represented as XO?

XO.

How is the surface area of a cube calculated?

Surface area = (length of side)² × 6.

If the length of a fine particle cube is 10 times smaller than a coarse particle cube, how does their surface area to volume ratio compare?

The surface area to volume ratio of the fine particle is 10 times greater.

What are isotopes?

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.

What are the mass numbers and percentage abundances of the isotopes of gallium?

Mass number 69 has 60% abundance, mass number 71 has 40% abundance.

How do you calculate the relative atomic mass (Ar) of gallium?

Ar = (mass number × percentage abundance) / 100, summed for all isotopes.

What is the most likely formula of a gallium ion?

Ga³⁺.

What is the significance of the periodic table's Group 3?

Gallium (Ga) is located in Group 3, indicating its valence electron configuration.

What happens to the boiling points of noble gases as you move down the group?

They increase.

What is the relationship between the number of protons and electrons in a neutral atom?

They are equal.

What is the role of neutrons in isotopes?

Neutrons contribute to the mass and stability of the nucleus but do not affect the charge.

What is the empirical formula for a compound with the formula XO?

XO.

In the context of atomic structure, what does the term 'mass number' refer to?

The total number of protons and neutrons in an atom's nucleus.

What is the significance of the percentage abundance of isotopes?

It indicates how common each isotope is in a natural sample of the element.

What is the difference between a compound and a mixture?

A compound consists of chemically bonded elements, while a mixture contains physically combined substances.

What is the importance of the surface area to volume ratio in particles?

It affects the reactivity and properties of the particles.

What type of structure does an oxide of a metal typically have?

Ionic or covalent structure depending on the metal and oxygen.

What is the significance of the term 'nanoparticle' in chemistry?

Nanoparticles have unique properties due to their small size, affecting their surface area to volume ratio.

What discovery helped Mendeleev's periodic table become accepted?

The discovery of gallium, which confirmed the existence of predicted elements and validated the periodic law.

What particle was discovered that changed the model of the atom from indivisible spheres?

Electron

What is the name of the model of the atom that includes a nucleus?

Nuclear model

What type of particles were fired at gold atoms in the experiment that led to a new atomic model?

Alpha particles

Which scientist first suggested that electrons orbit the nucleus at specific distances?

Niels Bohr

What do atoms of the same element have in common regarding atomic number?

They have the same number of protons.

Why can atoms of the same element have different mass numbers?

They have different numbers of neutrons.

What ensures that atoms have no overall charge?

They have the same number of protons and electrons.

What is the approximate radius of a nucleus?

1 × 10-14 m

If a nucleus is represented by a ball of radius 1 cm, what could represent the atom on the same scale?

A planet of radius 1000 km.

What are three differences between the nuclear model and the plum pudding model?

1. The nuclear model has a nucleus, while the plum pudding model does not. 2. The nuclear model has electrons orbiting the nucleus, whereas the plum pudding model has electrons embedded in a positive 'soup'. 3. The nuclear model describes a mostly empty space in atoms, while the plum pudding model suggests a more solid structure.

What change did Niels Bohr make to the nuclear model?

He proposed that electrons orbit the nucleus in fixed paths or energy levels.

Why can't the suggestion that Mendeleev reversed the order of elements to arrange them by atomic number be correct?

Because Mendeleev arranged elements by atomic weight, and the atomic number was not understood or defined at that time.

What are the parts of an atom labelled A and B in Figure 1?

A is the nucleus and B is the electron.

Which particle has the lowest mass?

The electron.

Which group of the periodic table contains element Z?

Group (specific group number would be from Figure 1).

What is the atomic number of element Z?

(specific atomic number from Figure 1).

What is the mass number of element Z?

(specific mass number from Figure 1).

What is the name for atoms with the same number of protons but different numbers of neutrons?

Isotope.

What is the relative atomic mass (Ar) of bromine?

80

What statement is true about the number of each type of bromine atom?

(specific statement from the options given in the notes).

Which substance is only one compound in Figure 1?

(specific substance A, B, C, D, or E from Figure 1).

Which substance is a mixture of elements in Figure 1?

(specific substance A, B, C, D, or E from Figure 1).

Which substance is a mixture of an element and a compound in Figure 1?

(specific substance A, B, C, D, or E from Figure 1).

What method is used to separate sand from water?

Filtration.

What is the expected temperature shown on the thermometer during distillation of salt solution?

100 °C.

Describe the process of distillation to produce pure water from salt solution.

(specific description based on the distillation process).

What are the two types of subatomic particles mentioned in the notes?

(specific subatomic particles from the table in the notes).

What is the function of the nucleus in an atom?

It contains protons and neutrons, contributing to the atomic mass.

What role do electrons play in an atom?

They are involved in chemical bonding and determine the atom's charge.

What is the significance of the atomic number?

It represents the number of protons in an atom and defines the element.

What is the significance of the mass number?

It is the total number of protons and neutrons in an atom.

How can mixtures be separated?

Using methods such as filtration, distillation, or chromatography.

What is the difference between a compound and a mixture?

A compound consists of two or more elements chemically bonded, while a mixture is a combination of substances that retain their individual properties.

What is the definition of a molecule?

A group of two or more atoms bonded together.

What is an ion?

An atom or molecule that has gained or lost one or more electrons, resulting in a charge.

What is a compound?

A substance formed when two or more elements are chemically bonded together.

What is the definition of mass number?

The mass number is the total number of protons and neutrons in an atom's nucleus.

Why do isotopes of an element have different mass numbers?

Isotopes have different mass numbers because they contain different numbers of neutrons.

What did the plum pudding model suggest about the structure of the atom?

The plum pudding model suggested that the atom was a ball of positive charge with electrons embedded in it.

How did the alpha particle scattering experiment change the model of the atom?

The alpha particle scattering experiment provided evidence that led to the conclusion that the atom has a small, dense nucleus, changing the model from the plum pudding model.

What method of separation is used for ethanol from a mixture with water?

Simple distillation.

What method of separation is used for salt from sea water?

Crystallisation.

What method of separation is used for the different colors in black ink?

Chromatography.

What method of separation is used for separating mixtures of liquids with different boiling points?

Fractional distillation.

In simple distillation, what happens to the liquid when it is heated?

The liquid evaporates.

In simple distillation, what happens to the vapor after it is cooled?

The vapor condenses.

What is a mixture of metals called?

An alloy.

Why is a mixture of metals harder than a pure metal?

The layers in the mixture are distorted, preventing them from sliding easily.

What is the volume of a nanoparticle that is a cube with each side measuring 20 nm?

8000 nm³.

What is located at the center of the atom?

The nucleus.

What are the two types of particles found in the nucleus of an atom?

Protons and neutrons.

Who proved the existence of the neutron?

James Chadwick.

Which particle orbits the center of the atom according to Niels Bohr?

The electron.

What is the relative charge of a neutron?

Neutral (0).

What is the relative mass of a neutron?

1

What is the purpose of filtration in separating mixtures?

To separate solid particles from liquids or gases.

What is the significance of the alpha particle scattering experiment in atomic theory?

It demonstrated that atoms have a dense nucleus and are mostly empty space.

What happens to the atoms in a pure metal compared to a mixture of metals?

In a pure metal, the atoms are arranged in regular layers, while in a mixture, the layers are distorted.

What is the process of separating a solid from a liquid using a barrier called?

Filtration.

What is the term for a charged particle formed when an atom gains or loses electrons?

Ion.

What are the two types of particles with the same mass?

The neutron and the proton.

How do you calculate the relative atomic mass (Ar) of an element using isotopes?

Ar = (mass number of isotope 1 × percentage abundance of isotope 1 + mass number of isotope 2 × percentage abundance of isotope 2) / 100.

What is the relative atomic mass (Ar) of element X with isotopes 63 (70% abundance) and 65 (30% abundance)?

Ar = (63 × 70 + 65 × 30) / 100 = 63.6.

What is the identity of element X based on its isotopes?

Element X is Copper (Cu).

What is the radius of an atom of element X in standard form?

1.2 × 10^-10 m.

What does the mass number of an atom represent?

The total number of protons and neutrons in the nucleus.

What are lithium atoms with different numbers of neutrons called?

Isotopes.

Which particle in an atom has a positive charge?

The proton.

Which particle in an atom has the smallest mass?

The electron.

What is the mass number of a lithium atom with 3 protons and 4 neutrons?

The mass number is 7.

How many neutrons are in a lithium atom with a mass number of 7?

4 neutrons.

Who discovered the neutron?

James Chadwick.

How do you estimate the relative atomic mass of an element with isotopes 69 (60% abundance) and 71 (40% abundance)?

Estimate Ar to be between 69.5 and 70.0.

What did Chadwick's experimental work contribute to the understanding of isotopes?

It led to the discovery of the neutron, explaining why isotopes of an element have different masses.

What is the percentage abundance of isotope 1 in the example given?

20% for isotope 10.

What is the percentage abundance of isotope 2 in the example given?

80% for isotope 11.