Y10 Chemistry/Physics Revision

quizlet pmo

What is an atom?

The smallest unit of an element that retains the chemical properties of that element.

What are the three main subatomic particles?

Protons, neutrons and electrons.

What is the charge of a proton?

+1 (positive).

What is the charge of a neutron?

0 (neutral).

What is the charge of an electron?

−1 (negative).

Where are protons found?

In the nucleus of an atom.

Where are neutrons found?

In the nucleus of an atom.

Where are electrons found?

In electron shells or energy levels surrounding the nucleus.

What is atomic number?

The number of protons in the nucleus of an atom.

What does the atomic number identify?

The element.

What is mass number?

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

How do you calculate the number of neutrons?

Mass number − atomic number.

What is an isotope?

An atom of the same element with the same number of protons but a different number of neutrons.

Why do isotopes of an element have similar chemical properties?

They have the same number and arrangement of electrons.

What is an element?

A pure substance made of only one type of atom.

What is a compound?

A substance made when atoms of different elements are chemically bonded together.

What is a molecule?

A group of two or more atoms chemically bonded together.

What is an ion?

An atom or group of atoms with a net electrical charge caused by gaining or losing electrons.

What is a cation?

A positively charged ion formed when an atom loses electrons.

What is an anion?

A negatively charged ion formed when an atom gains electrons.

What is an electron shell?

A region around the nucleus where electrons are arranged according to energy levels.

Why are electrons important in chemical bonding?

The arrangement of an atom's outer electrons determines how it interacts and bonds with other atoms.

What are valence electrons?

Electrons in the outermost occupied electron shell of an atom.

Why are valence electrons important?

They are primarily involved in chemical bonding.

What is a chemical bond?

A force of attraction that holds atoms or ions together.

What is ionic bonding?

The electrostatic attraction between oppositely charged ions formed through electron transfer.

What happens to electrons during ionic bonding?

Electrons are transferred from one atom to another.

What type of elements commonly form ionic compounds?

Metals and non-metals.

What happens to a metal atom during ionic bonding?

It usually loses electrons and becomes a positive ion.

What happens to a non-metal atom during ionic bonding?

It usually gains electrons and becomes a negative ion.

Why do ionic compounds form?

Oppositely charged ions attract each other through electrostatic forces.

What is a covalent bond?

A bond formed when atoms share electrons.

What type of elements commonly form covalent bonds?

Non-metals.

What happens to electrons in a covalent bond?

They are shared between atoms.

What is an ionic compound?

A compound consisting of positively and negatively charged ions held together by electrostatic attraction.

What is a covalent compound?

A compound consisting of atoms joined by covalent bonds.

What is the difference between ionic and covalent bonding?

Ionic bonding involves electron transfer and attraction between ions, while covalent bonding involves sharing electrons between atoms.

What is the formula for sodium chloride?

NaCl.

Why is sodium chloride written as NaCl?

Na forms Na⁺ and chlorine forms Cl⁻, so one of each ion is needed for a neutral compound.

What is the formula for magnesium chloride?

MgCl₂.

Why is magnesium chloride MgCl₂?

Mg²⁺ requires two Cl⁻ ions to produce an electrically neutral compound.

What is the formula for calcium oxide?

CaO.

What is the formula for aluminium oxide?

Al₂O₃.

What is the formula for magnesium oxide?

MgO.

What is the formula for water?

H₂O.

What is the formula for carbon dioxide?

CO₂.

What is the formula for methane?

CH₄.

What does a chemical formula tell you?

Which elements are present and the number or ratio of their atoms.

What does a subscript in a chemical formula represent?

The number of atoms of the preceding element in one molecule or formula unit.

What is the periodic table?

A table that organises elements according to their atomic number and recurring chemical properties.

What is a group in the periodic table?

A vertical column of elements.

Why do elements in the same group often have similar chemical properties?

They have similar numbers of valence electrons.

What is a period in the periodic table?

A horizontal row of elements.

What happens to atomic number across a period?

It generally increases from left to right.

What are metals?

Elements that generally conduct heat and electricity and tend to lose electrons in chemical reactions.

What are non-metals?

Elements that generally do not conduct heat or electricity well and tend to gain or share electrons.

What is a chemical reaction?

A process in which atoms are rearranged to form one or more new substances.

What are reactants?

The substances present at the beginning of a chemical reaction.

What are products?

The new substances formed during a chemical reaction.

What does a chemical equation represent?

The reactants, products and relative amounts involved in a chemical reaction.

What is a word equation?

A chemical equation written using the names of substances.

What is a symbol equation?

A chemical equation written using chemical formulae and symbols.

What is a balanced chemical equation?

An equation with the same number of atoms of each element on both sides.

Why must chemical equations be balanced?

Because atoms are conserved during a chemical reaction.

What is the law of conservation of mass?

Mass is not created or destroyed during a chemical reaction.

What is a precipitation reaction?

A reaction in which two solutions react to form an insoluble solid called a precipitate.

What is a precipitate?

An insoluble solid formed from a solution during a chemical reaction.

What is an acid?

A substance that produces hydrogen ions (H⁺) in aqueous solution.

What is a base?

A substance that reacts with acids and can neutralise them.

What is an alkali?

A soluble base that produces hydroxide ions (OH⁻) in water.

What is neutralisation?

A reaction between an acid and a base that produces a salt and usually water.

What is the general equation for acid + base?

Acid + base → salt + water.

What happens when an acid reacts with a metal?

A salt and hydrogen gas are generally produced.

What is the general equation for acid + metal?

Acid + metal → salt + hydrogen.

What happens when an acid reacts with a carbonate?

A salt, water and carbon dioxide are generally produced.

What is the general equation for acid + carbonate?

Acid + carbonate → salt + water + carbon dioxide.

What is a salt in chemistry?

An ionic compound formed when the hydrogen ion of an acid is replaced by a metal ion or another positive ion.

What is the pH scale?

A scale used to indicate how acidic or alkaline a solution is.

What pH values are acidic?

Values below 7.

What pH value is neutral?

pH 7.

What pH values are alkaline?

Values above 7.

What happens to acidity as pH decreases?

The solution becomes more acidic.

What happens to alkalinity as pH increases above 7?

The solution becomes more alkaline.

What is a catalyst?

A substance that changes the rate of a chemical reaction without being consumed overall.

What is reaction rate?

The speed at which reactants are converted into products.

How can temperature affect reaction rate?

Increasing temperature generally increases reaction rate.

Why does increasing temperature usually increase reaction rate?

Particles move faster and collide more frequently and with greater energy.

How does concentration affect reaction rate?

Increasing concentration generally increases reaction rate.

Why does increasing concentration increase reaction rate?

There are more reactant particles in a given volume, increasing collision frequency.

How does surface area affect reaction rate?

Increasing the surface area of a solid reactant generally increases reaction rate.

Why does greater surface area increase reaction rate?

More reactant particles are exposed and available for collisions.

How does a catalyst affect reaction rate?

It provides an alternative reaction pathway with a lower activation energy.

What is activation energy?

The minimum energy required for a chemical reaction to occur.

What is collision theory?

The idea that particles must collide with sufficient energy and appropriate orientation for a reaction to occur.

What evidence can indicate that a chemical reaction has occurred?

Formation of a new substance, colour change, gas production, precipitate formation, temperature change or light emission.

What is a physical change?

A change that does not produce a new substance.

What is a chemical change?

A change that produces one or more new substances.

What is energy transfer?

The movement of energy from one object or system to another.

What is energy transformation?

A change from one form of energy into another form.

What is energy conservation?

The principle that energy cannot be created or destroyed, only transferred or transformed.