Compostos i Elements Químics

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Questions and Answers

Un compost és una substància formada pel lligam de dos o més ______ de la taula periòdica que es poden separar en altres més senzills mitjançant mètodes químics (reaccions).

elements

L'aigua és un compost que es pot separar en oxigen i hidrogen mitjançant electròlisi.

True

Els ______ són capaços de formar lligams químics.

àtoms

Els àtoms d'un mateix element tenen sempre el mateix nombre de protons.

True Signup and view all the answers

El nombre de protons en el nucli d'un àtom s'anomena ______.

nombre atòmic Signup and view all the answers

Quina és la diferència entre un element i un compost?

Un element és una substància pura que no es pot descompondre en altres substàncies més senzilles. Un compost és un tipus de substància formada per la combinació química d'un mínim de dos elements diferents en una proporció definida. Signup and view all the answers

Els elements es poden descompondre mitjançant reaccions químiques.

False Signup and view all the answers

Quins són els tres tipus de partícules subatòmiques que formen els àtoms?

Els tres tipus de partícules subatòmiques que formen els àtoms són protons, neutrons i electrons. Signup and view all the answers

Quina és la diferència entre un àtom i un ió?

Un àtom és una unitat bàsica de la matèria que té el mateix nombre de protons i electrons, per tant, no té càrrega elèctrica. En canvi, un ió és un àtom que ha guanyat o perdut electrons, la qual cosa li confereix una càrrega elèctrica. Signup and view all the answers

What are the three subatomic particles that make up an atom?

Protons, neutrons, and electrons Signup and view all the answers

The atomic number of an element is determined by the number of protons in the nucleus.

True Signup and view all the answers

What is the term for the area of space around the nucleus where there is a high probability of finding an electron?

Atomic orbital Signup and view all the answers

The quantum mechanical model of the atom states that electrons move around the nucleus in fixed, circular orbits.

False Signup and view all the answers

Which of these is NOT one of Dalton's atomic theory tenets?

Atoms can be created or destroyed in chemical reactions. Signup and view all the answers

What is the term for a group of atoms that behave as a unit and are held together by chemical bonds?

Molecule Signup and view all the answers

What is the name of the model that describes the atom as having a nucleus surrounded by electrons in specific energy levels?

Bohr's model Signup and view all the answers

What is the term used to describe atoms of the same element that have the same atomic number, but different mass numbers?

Isotopes Signup and view all the answers

What is the average mass of all the isotopes of an element, taking into account their relative abundances?

Atomic mass Signup and view all the answers

What is the process called by which electrons are arranged in specific energy levels and orbitals around an atom?

Electron configuration Signup and view all the answers

Study Notes

Chemical Compounds and Elements

A compound is formed when two or more elements from the periodic table bond together. These can be broken down into simpler substances through chemical reactions.
Examples include water (H₂O), which can be separated into hydrogen and oxygen through electrolysis.
Atoms in compounds and elements are held together by chemical bonds.

Chemical Elements

A chemical element is a type of matter composed of atoms with identical properties.
Atoms have a nucleus containing protons and neutrons, and electrons orbiting the nucleus.
Each element has a unique number of protons called the atomic number.
Elements cannot be broken down chemically.
Atoms of the same element can have different numbers of neutrons, forming isotopes. Isotopes have the same number of protons but different mass numbers.

Properties of Chemical Elements

Scientists have organized elements based on their chemical properties.
The periodic table is a way of classifying elements based on their properties, evolving over time as more elements are discovered.
Early classification systems were based on atomic mass.

Atoms and Their Properties

Democritus (400 BCE) proposed that matter is made up of indivisible particles called atoms.
Dalton (1808) refined this with his atomic theory, which suggests important concepts about atoms including:
- Matter is composed of indivisible atoms.
- All atoms of the same element are identical in mass and chemical properties.
- Different elements have different kinds of atoms
- Atoms combine to form compounds. The ratios of atoms in a compound are whole numbers. Reactants are broken down and rearranged
Thomson's model proposed a "plum pudding" model, a sphere of positive charge with negatively charged electrons embedded within.
Rutherford's model suggested a small dense positively charged nucleus with electrons orbiting it.
Bohr's model described electrons orbiting the nucleus in specific energy levels.
The quantum mechanical model depicts electrons as existing in orbitals, regions of space where there's a high probability of finding electrons.

Dalton's Atomic Model

Tenet 1: Atoms are indivisible and unchangeable.
Tenet 2: Atoms of the same element are identical in mass and properties, and different from atoms of other elements.
Tenet 3: Compounds are formed when atoms from different elements combine in whole-number ratios.
Tenet 4: Atoms are exchanged during chemical reactions, but none are created or destroyed.

Thomson's Atomic Model

Thomson's model suggested a sphere of positive charge with negatively-charged electrons embedded within.

Rutherford's Atomic Model

Rutherford's model proposed a dense, positively charged nucleus at the center of the atom, with electrons orbiting around it.

Bohr's Atomic Model

Bohr's model suggested that electrons orbit the nucleus in specific energy levels.

Quantum Mechanical Model

Electrons exist in orbitals, areas of space where there's a high probability of finding them.
The quantum mechanical model is based on mathematical equations, describing the behavior of electrons.
Quantum numbers (principal, azimuthal, magnetic, and spin) define the electron's properties in the model

Atomic Number and Mass Number

The atomic number (Z) is the number of protons in an atom's nucleus.
The mass number (A) is the sum of protons and neutrons in an atom's nucleus.
Isotopes are atoms of the same element with different numbers of neutrons (same atomic number but different mass numbers).

Atomic Mass

Atomic mass is the weighted average of the masses of all the isotopes of an element, taking into account their relative abundances.

Electron Configuration

Electrons fill orbitals and energy levels based on increasing energy levels and certain rules.
Electron Configurations represent the arrangement of electrons in atomic orbitals.

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Description

Explora les propietats i estructures dels compostos i elements químics. Descobreix com es formen, les seves característiques i la seva organització en la taula periòdica. Aquest qüestionari et desafiarà amb preguntes sobre estructures atòmiques i reaccions químiques.